Increase In Osmotic Fragility Research Articles

Electrolyte and Electrocardiogram Changes in Dehydrated Male Bovine Calves

Background: Since many electrolytes are invariably lost in the diarrheal fluid, their serum alterations would have a profound bearing on the ECG. Methods: The study was conducted on twelve diarrhoeic and dehydrated male bovine calves of 2-5 months of age. Electrocardiogram and some haemato-biochemical parameters were compared between dehydrated and hydrated animals after supportive treatment. Result: Heart rate was found to be increased from 90.33 ± 9.71 bpm to 104.33 ± 9.03 bpm with considerable cardiac arrhythmias in dehydrated animals. Significantly (P less than 0.05) decreased QRS amplitudes and ST intervals were seen in dehydrated animals, whereas QRS durations were significantly increased. P waves were sometimes flattened or not visible, while T waves often were tall and peaked in diarrhoeic calves. No other significant changes in ECG parameters including cardiac axis were noticed. Non-significant increase in erythrocyte count and haematocrit associated with haemoconcentration was found. There was however a significant increase in lymphocyte and eosinophil count, together with increase in osmotic fragility in dehydrated animals. Electrolytes sodium and magnesium decreased significantly, while potassium increased amongst dehydrated calves. Based on observable ECG changes, alterations were indifferent from those of hyperkalemia, hyponatremia and hypomagnesemia. It is hoped that the present communication would be a helpful guide for the clinical veterinarian or those electrocardiographically monitoring supportive therapy of dehydrated animals.

The impact of circulation in a heart-lung machine on function and survival characteristics of red blood cells.

Extracorporeal circulation is accompanied by changes in red blood cell morphology and structural integrity that affect cell function and survival, and thereby may contribute to the various side effects of heart–lung machine‐assisted surgery. Our main objectives were to determine the effect of circulation of red blood cells in a stand‐alone extracorporeal circuit on several parameters that are known to be affected by, as well as contribute to red blood cell aging. As a source of RBCs, we employed blood bank storage units of different ages. In order to assess the relevance of our in vitro observations for the characterization of extracorporal circulation technology, we compared these changes in those of patients undergoing extracorporeal circulation‐assisted cardiac surgery. Our results show that circulation in a heart–lung machine is accompanied by changes in red blood cell volume, an increase in osmotic fragility, changes in deformability and aggregation behavior, and alterations in the exposure of phosphatidylserine and in microvesicle generation. RBCs from 1‐week‐old concentrates showed the highest similarities with the in vivo situation. These changes in key characteristics of the red blood cell aging process likely increase the susceptibility of red blood cells to the various mechanical, osmotic, and immunological stress conditions encountered during and after surgery in the patient’s circulation, and thereby contribute to the side effects of surgery. Thus, aging‐related parameters in red blood cell structure and function provide a foundation for the validation and improvement of extracorporeal circulation technology.

Supernatant reduction of stored gamma-irradiated red blood cells minimizes potentially harmful substances present in transfusion aliquots for neonates.

In neonate transfusion, the use of a dedicated red blood cell (RBC) unit decreases donor exposure. A separate safety measure involves gamma irradiation of the RBCs to abrogate the possibility of transfusion-associated graft-versus-host disease. However, in combination, storage of gamma-irradiated RBCs leads to accumulation of potentially harmful substances in the supernatant. For this study, RBCs were pooled and split into three study arms. Centrifugation or gravity was used to pack RBCs of matched units thereby reducing the amount of supernatant that would be present in neonate transfusion aliquots; these were compared to matched control units. Supernatant measurements of potassium, hemoglobin (Hb), RBC microvesicle (RMV) content, and mannitol were made in aliquots prepared weekly up to 21 days after gamma irradiation. RBC morphology and osmotic fragility were also assessed to determine if supernatant reduction methods affected the storage lesion. Potassium and mannitol were significantly decreased in transfusion aliquots prepared with either of the supernatant reduction methods. On Day 21, potassium levels from supernatant-reduced aliquots were below those of Day 7 control aliquots. A decrease in free Hb was only detected on Day 21 in centrifuged aliquots. RMVs were significantly reduced in centrifuged aliquots and significantly increased in gravity-settled aliquots. The only measurable effect on storage lesion was a small increase in osmotic fragility of the RBCs subjected to supernatant reduction. Supernatant reduction by centrifugation effectively reduces potassium, mannitol, and RMVs in aliquots from gamma-irradiated RBCs stored up to 21 days.

Mechanism of action involved in the hepatoprotective activities of methanol extract of Cassytha filiformis L. aerial parts in CCl4-induced liver damage

Cassytha filiformis alcohol decoction is used by traditional healers in Idem-Ogwa, Mbaitoli Local Government Area of Imo State, Nigeria, in the treatment of liver disorders ranging from hepatitis to susceptive poisoning and alcohol intoxication. The methanol extract of the aerial parts of Cassytha filiformis L. was investigated for hepatoprotective activity in rats challenged with carbon tetrachloride (CCl4). Apart from group 1 (normal), all other groups were pre-challenged with a single intraperitoneal injection of 0.7 ml of 20 % (v/v) CCl4 solution in olive oil. Group 2 (negative control) was given distilled water (10 ml kg−1, p.o.). Group 3 were treated with silymarin (35 mg kg−1 p.o.). Groups 4, 5, and 6 received oral treatments of 75, 150, and 300 mg kg−1 of the extract of C. filiformis respectively. All treatments were given by stomach intubation and at 12 h intervals for 7 days. Sodium pentobarbitone-induced sleeping time assay was carried out on the animals at 12 h after the last treatment on day 7 by intraperitoneal administration of Na-pentobarbitone (35 mg kg−1). Serum from individual animal was used to determine the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin, total protein and in vitro red blood cell membrane stability. The extract was safe up to 2000 mg kg−1 orally and did not induce overt clinical manifestation or death in rats. The extract significantly (p < 0.01) demonstrated potency at all test doses (75, 150, and 300 mg kg−1) in CCl4-challenged and treated animals when compared with prolonged Na-pentobarbitone-induced sleeping time observed in untreated CCl4-intoxicated rats. The methanol extracts of C. filiformis (150 and 300 mg kg−1) were also able to reduce hepatic tissue injury as revealed by a reduction in the serum levels of AST, ALT, ALP, and total bilirubin significantly (p < 0.05) but increased total serum protein significantly (p < 0.05) relative to values in untreated CCl4-induced liver damaged rats. Exposure of rat erythrocytes to varying saline concentrations (0.2–1.0 mg mL−1) of the extract did not produce observable measured increase in osmotic fragility in the red blood cell membranes. The findings suggest that the methanol extract of the aerial parts of C. filiformis could be useful in protecting hepatocytes from toxins especially from alcohol intoxication.

Allium cepa Linn. (Liliaceae) (red onion) bulb aqueous extract increases membrane stability of red blood cells and ameliorates oxidative stress in diabetes

The aim of this study was to assess the effects of Allium cepa aqueous extract on red blood cell membrane stability and oxidative stress in streptozotocin-induced diabetic Wistar rats. Various alterations of red blood cell (RBC) membrane appear both in diabetes mellitus and during the physiological aging processes. Diabetes mellitus decreases the life span of red blood cells therefore, it may change the membrane stability by acting through its effect on the aging process. Fresh A. cepa bulbs were mashed and macerated in distilled water for 48 h. The freeze dried filtrate (413.7 g) was used for the experiment. Male rats (120–170 g) were made diabetic by a single intraperitoneal injection of streptozotocin (60 mg/kg). Animals with fasting blood sugar (FBS) of 10 mmol/l on day 3 post challenge were selected, grouped, and treated with aqueous extract of A. cepa for 21 days at doses of 50, 150, 300 mg/kg and glibenclamide (2 mg/kg). A negative (challenged and untreated) and a normal control (unchallenged and untreated) groups were included. On day 21, blood samples were collected through the retrobulbar plexus of the medial cantus of the eye for osmotic fragility and in vivo oxidative stress markers analysis. The results showing showed an increase in percent stabilization (through increasing median corpuscular fragility, MCF) with increasing dose of the extract treatment. It also showed an increase in serum catalase (CAT), glutathione (GSH), and superoxide dismutase (SOD) which were significant (p < 0.05) at 150 and 300 mg/kg when compared with the negative control. Malondialdehyde (MDA) was also significantly reduced in these groups with increasing dose of the extract. This study suggests that increase in osmotic fragility of red blood cells attributed to the disturbance in ionic motion through their membrane could be stabilized with aqueous extract of A. cepa. Also, the extract ameliorates oxidation caused by reactive oxygen species and other free radicals produced in diabetic states.

Ebselen exhibits glycation‐inhibiting properties and protects against osmotic fragility of human erythrocytes in vitro

Diabetic status is associated with an increase on oxidative stress markers in humans and animal models. We have investigated the in vitro effects of high concentrations of glucose on the profile of oxidative stress and osmotic fragility of blood from control and diabetic patients; we considered whether its antioxidant properties could afford some protection against glucose-induced osmotic fragility, and whether ebselen could act as an inhibitor of hemoglobin glycation. Raising blood glucose to 5-100 mmol/L resulted in a concentration-dependent increase of glycated hemoglobin (HbA1c; P < 0.001) and thiobarbituric acid reactive species (TBA-RS) content (P < 0.004). Non-protein SH groups (NPSH) also increased significantly as the concentration of glucose increased up to 30 mmol/L (P < 0.001). The osmotic fragility was more pronounced in blood of uncontrolled diabetic patients than in these non-diabetic subjects. Ebselen significantly reduced the glucose-induced increase in osmotic fragility and inhibited HbA1c formation (P < 0.0001). These results indicate that blood from patients with uncontrolled diabetes are more sensitive to osmotic shock than from patients with controlled diabetes and control subjects in relation to increased production of free radicals in vivo.

Effects of aluminum chloride on some trace elements and erythrocyte osmotic fragility in rats

Aluminum (Al) is a nonessential, toxic element to which humans are constantly exposed as a result of an increase in industrialization and improving technology practices. The aim of the study was to investigate the effects of different durations and doses of Al exposure on serum and tissue element levels and erythrocyte osmotic fragility in rats. A total of 40 male Wistar Albino rats were divided into five groups: control, group I (3 weeks, 8 mg/kg), group II (6 weeks, 8 mg/kg), group III (3 weeks, 16 mg/kg), and group IV (6 weeks, 16 mg/kg). Al chloride (AlCl3) was injected intraperitoneally (i.p.) five times a week. At the end of the experimental period, levels of Al, iron (Fe), copper (Cu), and zinc (Zn) in serum, liver, and kidney tissues were measured using inductively coupled plasma optical emission spectrometry. Osmotic fragility was determined using a spectrophotometer. The results of the experiment indicate that Al induced a statistically significant increase in Al and Fe concentrations in liver and serum as well as in Cu in the kidney. The Fe concentration in serum and kidney tissues was significantly lower in all the groups. As a result of our study, it may be concluded that tissue Al accumulation may lead to an increase in osmotic fragility of erythrocytes and abnormal trace element levels.

Hemolytic anemia in a female patient presenting for routine cholecystectomy

Hemolytic anemia in a female patient presenting for routine cholecystectomy

Red blood cell processing for cryopreservation: from fresh blood to deglycerolization

Cryostorage of red blood cells (RBCs) represents a valid alternative to liquid storage, since units can be preserved safely for at least a decade while conserving RBC viability. While cryostorage has attracted a great deal of attention clinically, little is known about the biochemistry and physiology of cryostored erythrocyte concentrates. In the present study, we investigated cryostorage of RBCs through monitoring of cell processing steps (from fresh blood, to glycerolization, thawing and deglycerolization/washing) through repeated assays of standard parameters (MCV, RDW-SD) and scanning electron microscopy. Cell processing for cryostorage resulted in increased RBC volumes. Shape alterations caused an increase in osmotic fragility and permeability to ions. A significant pH drop was observed which could not to be attributed to a higher metabolic rate, since the levels of lactate did not show substantial fluctuation during the cell processing steps tested in this study. Membrane anomalies are likely related to the hemolysis observed which preferentially affected the densest and oldest cell sub-populations, as confirmed by means of discontinuous density gradients. Our results indicate that cryostorage itself in presence of glycerol does not significantly affect RBCs. Most of the alterations observed were related to cell processing and, in particular, to the increase of cytosolic glycerol as a consequence of the glycerolyzation step. Further studies might profitably investigate replacing glycerol with non-penetrating cryoprotectants.

Red blood cell storage and cell morphology

In this study, we performed weekly assessment of morphology-related parameters through monitoring of CPD-SAGM leuco-filtered erythrocyte concentrates from blood withdrawal until the 42nd day of storage. Liquid storage of red blood cells (RBCs) delivers a blood-derived therapeutic, which is safe, available, effective and affordable for most patients who need transfusion therapy in developed countries. However, a growing body of accumulating controversial evidences, from either biochemical or retrospective clinical studies, prompted safety concerns about longer stored RBCs. Statistical image analysis through scanning electron microscope was coupled to osmotic fragility and erythrocyte sedimentation rate. We could observe that by day 21 more than 50% of RBCs displayed non-discocyte phenotypes. This observation was related to an increase in osmotic fragility, which was totally overlapped in day 0 controls and day 7 RBCs while only slightly augmented in day 14 samples. Cation dysregulation (pH internal/external alteration and potassium) might both reflect and trigger a negative feedback loop with metabolic fluxes and membrane cation pumps. Morphology parameters suggest that significant alterations to RBC morphology over storage duration occur soon after the 14th day of storage, as to become significant enough within the 21st day.

Structure-activity relationships regarding the antioxidant effects of the flavonoids on human erythrocytes

The effects of eleven flavonoids on lipid peroxidation, protein degradation, deformability and osmotic fragility of human erythrocytes exposed in vitro to 10 mM H2O2 for 60 min at 37˚C have been studied. The following flavonoids; quercetin, rutin and morin significantly protected erythrocytes against lipid peroxidation caused by H2O2. This inhibition of lipid peroxidation could be explained by the presence of at least two hydroxyl groups in ring B of the flavonoid structure, regardless of their positions. However, the flavonoids; quercetin, 3,5,7-trihydroxy-4'-methoxy flavone-7-rutinoside and 3-hydroxy flavone significantly protected erythrocytes against protein degradation. This inhibition could also be explained by the presence of a hydroxyl group at C-3 in ring C of the flavonoid structure. Quercetin and 3,5,7-trihydroxy-4'-methoxy flavone-7-rutinoside significantly protected erythrocytes against loss of deformability and increased osmotic fragility, indicating that the loss of erythrocyte deformability and the increase in osmotic fragility of erythrocytes exposed to H2O2 are related to protein degradation rather than to lipid peroxidation. The other flavonoids (chrysin, 2-carboxy ethyl dihydroxy flavone, apigenin, cirsimaritin, α-naphto flavone and flavanone) failed to protect erythrocytes against the observed oxidative damages. The results demonstrate the importance of the chemical groups substituted on the basic skeleton of the flavonoids in dictating the type of antioxidant activity, and also demonstrate the hemorheological potentials of flavonoids that have particular protein-antioxidant activities.

Sphingomyelinase-Induced Remodeling of the Erythrocyte Membrane

Abstract 1032Sphingomyelinases (SMases) catalyze the hydrolysis of sphingomyelin, a major lipid component of cell membranes, generating phosphocholine and ceramide. Inflammation arising from various diseases including sepsis is known to enhance SMase secretion in the circulation. Also, chronic inflammation typically induces anemia through reduced production and enhanced clearance of red cells, which is often associated with poor disease outcome. Incubation of red cells with plasma of septic patients with enhanced SMase activity has been described to result in ceramide formation and exposure of phosphatidylserine (PS). Therefore, we studied the effect of SMase on various pathophysiologically relevant parameters of red cell homeostasis in fresh and stored erythrocytes.Using time-lapse confocal microscopy we observed a typical sequence of events during SMase treatment of erythrocytes. The cells first lost their discoid shape, PS became externalized, and ultimately there was a sudden loss of cytoplasmic content. Additional confocal microscopy, flow cytometry and immunoblot analyses showed that SMase treatment resulted in ceramide-induced alterations in red cell membrane-cytoskeleton interaction and organization, including lipid raft formation. These changes probably underlie the increase in osmotic fragility, membrane vesiculation and invagination, as well as large hemoglobin aggregates that we also observed. The membrane lipid scrambling, altered morphology, enhanced fragility and presence of rigid membrane patches may all contribute to enhanced removal of sphingomyelinase-exposed red cells.Generation of very low ceramide levels in the membrane by SMase, as detected by Positive-Ion MALDI-TOF MS, already affected red cell shape, membrane rearrangement and osmotic responsiveness. Combined with the observation that 24 hour incubation of red cells with pathological SMase levels induced shape change and PS exposure, these data suggest that red cell homeostasis could well be disturbed by SMase during chronic inflammation. Of note, red cell storage greatly increased the sensitivity to SMase-induced changes. This may well have implications for red cell transfusion in critically ill patients. Disclosures:No relevant conflicts of interest to declare.

Regulatory volume response following hypotonic stress in Atlantic salmon erythrocytes

The purpose of this study was to examine regulatory volume decrease (RVD) in Atlantic salmon red blood cells (RBCs). Osmotic fragility was determined optically, mean cell volume was measured electronically, and changes in intracellular Ca(2+) concentration were visualized using fluorescence microscopy and fluo-4-AM. Cells displayed an increase in osmotic fragility and an inhibition of volume recovery following hypotonic shock when they were exposed to a high taurine Ringer or when placed in a high K(+) medium. Interestingly, RVD in cells from fish collected during the summer depended more on taurine efflux, whereas fall cells relied more on the loss of K(+). In addition, RVD in fall cells was prevented with the K(+) channel inhibitor quinine, whereas the ionophore gramicidin decreased osmotic fragility and potentiated volume recovery. Further, hypotonic shock (0.5X Ringer) for both summer and fall cells caused an increase in cytosolic Ca(2+), which resulted from influx of this ion because it was not observed when extracellular Ca(2+) was chelated with EGTA (10 nM free Ca(2+)). Cells exposed to a low Ca(2+) hypotonic Ringer also had a greater osmotic fragility and failed to recover from hypotonic swelling. Finally, inhibition of phospholipase A(2) with ONO-RS-082 blocked volume recovery. In conclusion, Atlantic salmon RBCs displayed volume decrease in response to hypotonic shock, which depended on a swelling-induced influx of Ca(2+) and an increase in the efflux of K(+) and taurine.

Heparina e Na2EDTA como anticoagulantes para surubim híbrido (Pseudoplatystoma reticulatum x P. corruscans): eficácia e alterações hematológicas

Este estudo avaliou o efeito da heparina 100UI e do Na2EDTA nas concentrações de 3, 5 e 10% sobre a coagulação sanguínea e os parâmetros hematológicos de surubim híbrido. Foram utilizados 10 peixes, com peso médio de 386,7±24,3g e comprimento total médio de 38,7±6,4cm, para colheita das amostras sanguíneas e determinação do percentual do hematócrito, teor de proteínas plasmáticas totais e teste de fragilidade osmótica dos eritrócitos (FOE). Os dados foram submetidos à análise de variância, e as médias foram comparadas pelo teste de Tukey, a 5% de probabilidade. A coagulação foi eficientemente inibida quando utilizado o Na2EDTA; já as amostras com heparina coagularam 10 horas após a coleta. Houve aumento na fragilidade osmótica dos eritrócitos (P&lt;0,01), especialmente quando utilizado o Na2EDTA 10 e 5%, não havendo diferença entre o controle e a heparina. No hematócrito e teor de proteínas plasmáticas totais, não foram verificadas diferenças significativas. O Na2EDTA 3% é seguro e eficiente como anticoagulante para surubim híbrido, prevenindo a coagulação por mais de 10h e ocasionando discreto efeito sobre a fragilidade osmótica dos eritrócitos.

Effect of Magnesium Sulfate on the Osmotic Fragility and Lipid Peroxidation of Intact Red Blood Cells from Pregnant Women with Severe Preeclampsia

Objective: To evaluate the osmotic fragility and level of lipid peroxidation of red blood cells from pregnant women with severe preeclampsia, treated or not with MgSO4. Methods: Osmotic fragility and lipid peroxidation of red blood cells was evaluated in 11 normotensive pregnant women and eleven pregnant women with severe preeclampsia. Results: MgSO4 therapy, either in vivo or in vitro, leads to a reduction of the osmotic fragility and the level of lipid peroxidation of red blood cells from pregnant women with severe preeclampsia. Conclusions: Interaction of MgSO4 with free radicals, by avoiding an excessive lipid peroxidation of the red blood cell membrane, would protect the membrane structure, avoiding in this way the increase in osmotic fragility.

Biochemical Changes of Hemoglobin and Osmotic Fragility of Red Blood Cells in High Fat Diet Rabbits

The aim of this study was to assess the effects of hyperlipidemia on auto-oxidation rate of hemoglobin (Hb; absorbance at 630 nm versus time), Hb derivatives and osmotic fragility of Red Blood Cells (RBCs). These parameters were measured in twenty five 12-week-old male New Zealand white rabbits fed on a High Fat Diet (HFD) for a feeding period of 10 weeks. We found that Hb concentration and RBC count were significantly decreased while white blood cell and platelet counts were significantly increased in HFD rabbits compared with control rabbits. The Total Cholesterol (TC) was significantly increased (p < 0.01) in HFD rabbits compared with control rabbits with percentage normalized change of 1198% and Low Density Lipoprotein Cholesterol (LDLC) significantly increased (p < 0.01) in HFD rabbits compared with control rabbits with percentage normalized change of 1591%. In HFD rabbits, oxyhemoglobin (HbO2) percentage was significantly decreased while met-hemoglobin (Met-Hb) percentage was significantly increased compared with control rabbits. The auto-oxidation rate was significantly higher in HFD rabbits compared with controls. Hyperlipidemia induced an increase in the osmotic fragility of RBCs and a decrease in their membrane elasticity compared with controls. This study suggests that hyperlipidemia may produce reactive oxygen species and other free radicals which increase the auto-oxidation rate of Hb and promote the conversion of HbO2 and the fractions of unstable Hb molecules to Met-Hb and carboxyhemoglobin. Increased platelet activation in hyperlipidemic rabbits may be of pathophysiological importance for the progression of atherosclerosis and thromboembolic complications. The increase in osmotic fragility of RBCs may be attributed to the disturbance of ionic motion through the membrane and the change in molecular properties of the membrane macromolecules.

Effects of elevated intracellular calcium on the osmotic fragility of human red blood cells

High throughput methodologies that measure the distribution of osmotic fragilities in red blood cell populations have enabled the investigation of dynamic changes in red cell homeostasis and membrane permeability in health and disease. The common assumption in the interpretation of dynamic changes in osmotic fragility curves is that left or right shifts reflect a decreased or increased hydration state of the cells, respectively, allowing direct inferences on membrane transport from osmotic fragility measurements. However, the assumed correlation between shifts in osmotic fragility and hydration state has never been directly explored, and may prove invalid in certain conditions. We investigated here whether this correlation holds for red cells exposed to elevated intracellular calcium. The results showed that elevated cell calcium causes a progressive increase in osmotic fragility with minimal contribution from cell hydration (<8%). Loss of membrane area by the release of 160±40nm diameter (mean±SD) vesicles is shown to be a major contributor, but may not account for the full non-hydration component. The rest must reflect a specific calcium-induced lytic vulnerability of the membrane causing rupture before the cells attain their maximal spherical volumes. The implications of these findings are discussed.

Erythrocyte osmotic fragility and lipid peroxidation in experimental hyperthyroidism

This study investigated the relation between erythrocyte osmotic fragility and oxidative stress and antioxidant state in primary hyperthyroidism induced experimental rats. Twenty-four Spraque-Dawley-type female rats weighing between 160 and 200 g were divided into two, as control (n = 10) and experimental (n = 12), groups. The experimental group animals have received tap water and L-Tiroksin (0.4 mg/100 g fodder) added standard fodder for 30 days to induce hyperthyroidism. Control group animals were fed tap water and standard fodder for the same period. Blood samples were drawn from the abdominal aorta of the rats under ether anesthesia. T₃, T₄, and TSH levels, osmotic fragility, malondialdehyde (MDA), superoxide dismutase, and glutathione levels were measured in the blood. There was a statistically significant deviation found in maximum and minimum osmotic hemolysis limit values of experimental group when compared to controls. The standard hemolytic increment curve of the hyperthyroid group shifted to the right when compared to control group's curve. There was a statistically significant increase found in MDA and superoxide dismutase, but statistically a significant decrease was detected in glutathione levels in hyperthyroid group when compared to controls. As a result of our study, it may be concluded that hyperthyroidism may led to an increase in osmotic fragility of erythrocytes and this situation may possibly originate from the increased lipid peroxidation in hyperthyroidism.

Antioxidant potential of thyme extract: alleviation of N-nitrosodiethylamine-induced oxidative stress

Protective role of thyme extract against N-nitrosodiethylamine (NDEA)-induced oxidative stress has been evaluated in albino rats. For this, one group of rats were fed diet supplemented with thyme extract (0.5%) and served as the test group, whereas animals of the other group fed on normal diet served as the control group. The rats were fed on respective diets for a period of 2 weeks after which stress was induced to half the animals of each group by i.p. administration of NDEA at 200 mg/kg body weight. Animals were killed 48 h post stress-induction period. Feed intake and body weight decreased significantly in both test and control groups, the effect being less in test group. Increase in osmotic fragility and in-vitro lipid peroxidation (LPO) on stress induction was of lower degree in the test group. NDEA toxicity was mainly reflected in liver as evidenced by increased activities of plasma aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. The effect was of lower degree in test group as compared with that in the control group. Increase in urea levels observed following NDEA administration was also of lower degree in test groups. Blood glutathione (GSH) levels increased more so in test group compared with control group on stress induction. The activities of superoxide dismutase (SOD), peroxidase (Px), and catalase (CAT) activities decreased significantly on stress induction in erythrocytes. LPO increased in all the tissues through varying degree, and the increase was appreciably of lower degree in test group. The activity of SOD increased significantly in both test and control group on stress induction, whereas activities of Px and CAT decreased following NDEA treatment, and the effects were of lower degree in test group. Thus, supplementation of diet with thyme extract can improve antioxygenic potential and hence help to prevent oxidative stress.

N-nitrosodiethylamine-induced toxicity in relation to oxidative stress and development of atherosclerosis in hypercholesterolemic diet-fed rabbits

N-nitrosodiethylamine (NDEA) is an important carcinogenic nitrosamine frequently present in human environment, besides being a part of the human food chain by virtue of its reported presence in various foodstuffs and beverages. This study was planned to investigate the toxicity of NDEA in relation to the development of atherosclerosis in experimental rabbits. Oral administration of NDEA at 50 mg per day along with hypercholesterolemic diet to rabbits resulted in significant increase in osmotic fragility of erythrocytes as well as increased in vitro lipid peroxidation (LPO) of erythrocytes. The plasma total lipids, cholesterol and glycerides continued to increase during the feeding of hypercholesterolemic diet with or without NDEA. However, after the cessation of hypercholesterolemic diet, decrease in the lipid fractions was relatively less in the experimental group receiving NDEA. Administration of NDEA in the hypercholesterolemic diet did not affect the total lipid content in the liver, although it marginally increased the hepatic cholesterol levels. Histopathological changes in different tissues (heart, aorta and liver) were relatively more severe in experimental rabbits receiving NDEA treatment as compared to the control ones. Our study therefore indicates that oral administration of NDEA results in increased LPO of blood and decreased lipid clearance, which may in turn result in increased degree of atherosclerosis.