Differential effect of omega3 PUFA supplementations on Na,K-ATPase and Mg-ATPase activities: possible role of the membrane omega6/omega3 ratio

Orally Administered Fumonisins Affect Porcine Red Cell Membrane Sodium Pump Activity and Lipid Profile Without Apparent Oxidative Damage

Weaned piglets (n = 3 × 6) were fed 0, 15 and 30 mg/kg diet fumonisin (FB₁, FB₂ and FB₃, i.e., FBs, a sphinganine analogue mycotoxin), from the age of 35 days for 21 days, to assess mycotoxin induced, dose-dependent changes in the red cells’ membrane. Ouabain sensitive Na⁺/K⁺ ATPase activity was determined from lysed red cell membranes, membrane fatty acid (FA) profile was analysed, as well as antioxidant and lipid peroxidation endpoints. Final body weight was higher in the 30 mg/kg group (vs. control), even besides identical cumulative feed intake. After 3 weeks, there was a difference between control and the 30 mg/kg group in red cell membrane sodium pump activity; this change was dose-dependent (sig.: 0.036; R² = 0.58). Membrane FA profile was strongly saturated with non-systematic inter-group differences; pooled data provided negative correlation with sodium pump activity (all individual membrane n6 FAs). Intracellular antioxidants (reduced glutathione and glutathione peroxidase) and lipid peroxidation indicators (conj. dienes, trienes and malondialdehyde) were non-responsive. We suppose a ceramide synthesis inhibitor (FB₁) effect exerted onto the cell membrane, proven to be toxin dose-dependent and increasing sodium pump activity, with only indirect FA compositional correlations and lack of lipid peroxidation.

Alterations in Serum Zinc and Polyunsaturated Fatty Acid Concentrations in Treatment-Naive HIV-Diagnosed Alcohol-Dependent Subjects with Liver Injury

Heavy alcohol drinking causes alterations in the metabolism of fatty acids and zinc that participate in inflammation and liver injury. HIV infection has been reported to cause dysregulated polyunsaturated fatty acid (PUFA) and zinc metabolism. In this pilot study, we examined the role of dysregulated PUFA metabolism and zinc deficiency in the liver injury occurring in heavy drinkers with early-stage HIV diagnosis. Fourteen heavy drinking alcohol-dependent (AD) patients [seven with treatment-naive HIV diagnosis (AD+HIV) and seven without HIV infection (AD)] participated in this study. Liver injury, serum zinc, PUFAs, viral load, CD4⁺ count, and drinking measures using lifetime drinking history (LTDH), and timeline follow-back past 90 days (TLFB90) were evaluated. Liver injury was also assessed in seven age- and gender-matched socially drinking HIV treatment-naive patients who served as disease controls. HIV viral load by itself did not show any correlation with liver injury. Liver enzymes were significantly elevated in both AD+HIV and AD patients, and AD+HIV patients had significantly higher alanine aminotransferase (ALT) levels than did AD patients, even with lower drinking. Serum zinc was significantly lower in AD+HIV patients. Only AD+HIV patients showed a significant elevation in linoleic acid (LA) and alpha-linoleic acid (ALA) levels. Serum zinc and ALT, LA and ALT, and ALA and ALT were significantly associated only in AD+HIV patients. The association between LA and ALT showed a higher effect than did the ALA and ALT association in the AD+HIV patients. Interestingly, AD+HIV subjects (who drank less), nevertheless, showed more liver injury compared with AD patients, who reported heavier drinking. We speculate that the underlying proinflammatory response resulting from zinc deficiency and an elevation in serum LA likely contributed to liver injury in AD+HIV patients, even with a comparatively lower degree of heavy drinking.

Asiaticoside attenuates diabetes-induced cognition deficits by regulating PI3K/Akt/NF-κB pathway

Diabetes-associated cognitive dysfunction, referred as "diabetic encephalopathy", has been confirmed in a great deal of literature. Current evidence support that oxidative stress, inflammation, energy metabolism imbalance, and aberrant insulin signaling are associated with cognition deficits induced by diabetes. The present study explore the effect of asiaticoside on the cognition behaviors, synapses, and oxidative stress in diabetic rats. Asiaticoside could markedly ameliorate the performance in the Morris Water Maze (decreased latency time and path length, and increased time spent in the target quadrant), which was correlated with its capabilities of suppressing oxidative stress, restoring Na(+)-K(+)-ATPase activity and protecting hippocampal synapses. In vitro, asiaticoside could up-regulate synaptic proteins expression via modulating Phosphoinositide 3-kinase (PI3K)/Protein Kinase B(AKT)/Nuclear Factor -kappa B (NF-κB)-mediated inflammatory pathway in SH-SY5Y cells incubated with high glucose chronically. In conclusion, asiaticoside had beneficial effects on the prevention and treatment of diabetes-associated cognitive deficits, which was involved in oxidative stress, PI3K/Akt/NF-κB pathway and synaptic function in the development of cognitive decline induced by diabetes.

Individual and combined haematotoxic effects of fumonisin B(1) and T-2 mycotoxins in rabbits

Weaned rabbits were fed diets contaminated with 2 mg/kg diet T-2 toxin alone, or 10 mg/kg diet fumonisin B1 (FB1) alone, and both toxins in combination (2+10 mg/kg, resp.), as compared to a toxin free control. Samplings were performed after 2 and 4 weeks. Bodyweight of the T-2 fed group was lower after 4 weeks; the liver weight increased dramatically. Red blood cell (RBC) Na(+)/K(+) ATPase activity decreased after 4 weeks in the T-2 group, it increased in the FB1 group and antagonism was found by the combined treatment. The RBC membrane fatty acid profile was modified by both toxins similarly during the entire feeding. After 4 weeks T-2 alone and in combination (with FB1) was found to increase mean cell volume (MCV). The time-dependent alterations in the T-2 group were significant for MCV (increase) and the mean cell haemoglobin (increase). The active monovalent cation transport was altered by both mycotoxins. Most probably FB1 exerts its sodium pump activity modification via an altered ceramide metabolism (behenic acid decrease in the RBC membrane), while for T-2 toxin a moderate membrane disruption and enzyme (protein) synthesis inhibition was supposed (ca. 75% decrease of the sodium pump activity).

Gender specific influence of fish oil or atorvastatin on functional properties of renal Na,K-ATPase in healthy Wistar and hypertriglyceridemic rats

For better understanding of pathophysiological processes leading to increased retention of sodium as a consequence of hyperlipidemia, the properties of renal Na,K-ATPase, a key enzyme involved in maintaining sodium homeostasis in the organism, were studied. Enzyme kinetics of renal Na,K-ATPase were used for characterization of ATP- and Na(+)-binding sites after administration of fish oil (FO) (30 mg·day(-1)) or atorvastatin (0.5 mg·100 g(-1)·day(-1)) to healthy Wistar rats and rats with hereditary hypertriglyceridemia of both genders. Untreated healthy Wistar and also hypertriglyceridemic female rats revealed higher Na,K-ATPase activity as compared to respective untreated male groups. Hypertriglyceridemia itself was accompanied with higher Na,K-ATPase activity in both genders. Fish oil improved the enzyme affinity to ATP and Na(+), as indicated by lowered values of K(m) and K(Na) in Wistar female rats. In Wistar male rats FO deteriorated the enzyme in the vicinity of the Na(+)-binding site as revealed from the increased K(Na) value. In hypertriglyceridemic rats FO induced a significant effect only in females in the vicinity of the sodium binding sites resulting in improved affinity as documented by the lower value of K(Na). Atorvastatin aggravated the properties of Na,K-ATPase in both genders of Wistar rats. In hypertriglyceridemic rats protection of Na,K-ATPase was observed, but this effect was bound to females only. Both treatments protected renal Na,K-ATPase in a gender specific mode, resulting probably in improved extrusion of excessive intracellular sodium out of the cell affecting thus the retention of sodium in hHTG females only.

Hydroxyurea therapy mobilises arachidonic Acid from inner cell membrane aminophospholipids in patients with homozygous sickle cell disease

The cytotoxic compound hydroxyurea (HU) is effective therapy for sickle cell disease. However, its effect on unsaturated membrane lipids is unknown. Red cell fatty acids were investigated in HU-treated (n = 19) and HU-untreated (n = 17) sickle cell patients and controls (n = 20). The HU-treated compared with the HU-untreated patients had lower arachidonic (AA) acid level in ethanolamine, physphoglycerids (EPG) (22.9 ± 1.2 versus 24.0 ± 1.1%, P < 0.05) serine SPG (22.13 ± 2.2 versus 24.9 ± 2.3%, P < 0.01) phosphoglycerides. The treated patients and controls had comparable levels of docosahexaenoic (DHA) and total n-3 fatty acids in EPG and choline phosphoglycerides (CPG). In contrast, the untreated group had significantly (P < 0.05) lower DHA and total n-3 compared with the controls in EPG (2.7 ± 0.4 versus 3.2 ± 0.6% and 4.6 ± 0.5 versus 5.2 ± 0.7%) and CPG (0.7 ± 0.2 versus 1.0 ± 0.2% and 1.2 ± 0.2 versus 1.4 ± 0.3). HU is known to activate cytosolic phospholipase A2 and cyclooxygenase 2, and from this study, it appears to induce mobilisation of AA from the inner cell membrane EPG and SPG. Hence, eicosanoids generated from the released AA may play a role in clinical improvements which occur in HU-treated patients.

Cellular signatures in the primary visual cortex of phylogeny and placentation

The long-held view that brain size can be used as an index of general functional capacity across mammals is in conflict with increasing evidence for phyletic differences in cellular organization. Furthermore, it is poorly understood how the internal cellular organization of the brain covaries with overall brain size variation. Using design-based stereology, we quantified glial cell and neuronal densities in the primary visual cortex of 71 mammalian species (spanning 11 orders) to test how those cellular densities are influenced by phylogeny, behavior, environment, and anatomy. We further tested cellular densities against mode of placentation to determine whether a relationship may exist. We provide evidence for cellular signatures of phylogenetic divergence from the mammalian trend in primates and carnivores, as well as considerably divergent scaling patterns between the primate suborders, Strepsirrhini and Haplorrhini, that likely originated at the anthropoid stem. Finally, we show that cellular densities in the mammalian cortex relate to the variability of maternal resources to the fetus in a species.

Effects of n-3 PUFAs on breast cancer cells through their incorporation in plasma membrane

Background

PUFAs are important molecules for membrane order and function; they can modify inflammation-inducible cytokines production, eicosanoid production, plasma triacylglycerol synthesis and gene expression. Recent studies suggest that n-3 PUFAs can be cancer chemopreventive, chemosuppressive and auxiliary agents for cancer therapy. N-3 PUFAs could alter cancer growth influencing cell replication, cell cycle, and cell death. The question that remains to be answered is how n-3 PUFAs can affect so many physiological processes. We hypothesize that n-3 PUFAs alter membrane stability, modifying cellular signalling in breast cancer cells.

Methods

Two lines of human breast cancer cells characterized by different expression of ER and EGFR receptors were treated with AA, EPA or DHA. We have used the MTT viability test and expression of apoptotic markers to evaluate the effect of PUFAs on cancer growth. Phospholipids were analysed by HPLC/GC, to assess n-3 incorporation into the cell membrane.

Results

We have observed that EPA and DHA induce cell apoptosis, a reduction of cell viability and the expression of Bcl2 and procaspase-8. Moreover, DHA slightly reduces the concentration of EGFR but EPA has no effect. Both EPA and DHA reduce the activation of EGFR.

N-3 fatty acids are partially metabolized in both cell lines; AA is integrated without being further metabolized. We have analysed the fatty acid pattern in membrane phospholipids where they are incorporated with different degrees of specificity. N-3 PUFAs influence the n-6 content and vice versa.

Conclusions

Our results indicate that n-3 PUFA feeding might induce modifications of breast cancer membrane structure that increases the degree of fatty acid unsaturation. This paper underlines the importance of nutritional factors on health maintenance and on disease prevention.

Na, K-ATPase: Ubiquitous Multifunctional Transmembrane Protein and its Relevance to Various Pathophysiological Conditions

The Na(+), K(+)-ATPase (NKA) is an ubiquitous enzyme consisting of α, β and γ subunits, and is responsible for the creation and maintenance of the Na(+) and K(+) gradients across the cell membrane by transporting 3 Na(+) out and 2 K(+) into the cell. Sodium pump regulation is tissue as well as isoform specific. Intracellular messengers differentially regulate the activity of the individual NKA isozymes. Regulation of specific NKA isozymes gives cells the ability to precisely coordinate NKA activity to their physiological requirements. It is the only known receptor for the cardiac glycosides used to treat congestive heart failure and cardiac arrhythmias. Endogenous ligands structurally similar to cardiac glycosides may act as natural regulators of the sodium pump in heart and other tissues. Identification of naturally occurring regulators of  NKA could initiate the discovery of new hormone-like control systems involved in the etiology of selected disease processes, hence the importance of understanding the relation of the sodium pump and its ligands to disease. Diabetes has a marked effect on the metabolism of a variety of tissues and because the NKA is critical for the membrane potential and many transports, a change in its activity in diabetes would have profound consequence in these tissues. NKA is also involved in hypertension, salt balance, cardiovascular and renal disorders, sperm capacitation, cell volume regulation, apoptosis, rheumatoid arthritis, sepsis, neurological disorders, lung edema clearance and preeclampsia. NKA activity and expression in the collecting duct of kidney are modulated physiologically by hormones like aldosterone, vasopressin, and insulin. NKA enzyme activity and subunit levels are reduced in carcinoma, NKA-β levels were highly reduced in an invasive form of human renal clear cell carcinoma, androgen-dependent prostate cancer, in early stages of urothelial cancer, as well as in poorly differentiated, highly motile carcinoma cell lines obtained from various tissues suggesting a functional link between reduced NKA-β expression and cancer progression. It could be a target for the development of anticancer drugs as it serves as a signal transducer, it is a player in cell adhesion and its aberrant expression and activity are implicated in the development and progression of different cancers.

KEYWORDS

Na(+), K(+)-ATPase (NKA); Cardiotonic steroids (CTS); Diabetes; Hypertension; Cardiovascular and renal disorders; Signal transducer; Anticancer drugs.

Membrane basis for fish oil effects on the heart: linking natural hibernators to prevention of human sudden cardiac death

The concept that diet-induced changes in membrane lipids could modify heart function partly arose from observations that membrane composition and physical properties were closely associated with the capacity of the heart to respond appropriately to torpor and hibernation. Observations of natural hibernators further revealed that behavior of key membrane-bound enzymes could be influenced through the lipid composition of the cell membrane, either by changing the surrounding fatty acids through reconstitution into a foreign lipid milieu of different composition, or by alteration through diet. Myocardial responsiveness to beta-adrenoceptor stimulation, including initiation of spontaneous dysrhythmic contractions, was altered by both hibernation and dietary modulation of membrane fatty acids, suggesting modified vulnerability to cardiac arrhythmia. Subsequent studies using whole-animal models recognized that vulnerability to ventricular fibrillation decreased as the polyunsaturated: saturated fat (P:S) ratio of the diet increased. However, dietary fish oils, which typically contain at least 30% saturated fatty acids and only 30% long-chain n-3 (omega-3) polyunsaturated fatty acids (PUFA), exhibit antiarrhythmic effects that exceed the predicted influence of the P:S ratio, suggesting properties unique to the long-chain n-3 PUFA. Large-scale clinical trials and epidemiology have confirmed the arrhythmia prevention observed in vitro in myocytes, papillary muscles, and isolated hearts and in whole-animal models of sudden cardiac death. Some progress has been made towards a biologically plausible mechanism. These developments highlight nature's ability to provide guidance for the most unexpected applications.

Abnormality of erythrocyte membrane n-3 long chain polyunsaturated fatty acids in sickle cell haemoglobin C (HbSC) disease is not as remarkable as in sickle cell anaemia (HbSS)

Sickle cell disease (SCD) is a group of inherited blood disorders in which clinical illness results from the presence of erythrocytes with sickled haemoglobin (HbS). Blood vessel occlusion is a fundamental pathological process in SCD. Sickle cell haemoglobin C (HbSC) disease and sickle cell anaemia (HbSS) share some pathophysiology and clinical manifestations. However, the former is generally less severe. Erythrocytes of HbSC patients have longer life span, reduced haemolysis, and lower propensity to adhere to vascular endothelium than those of their HbSS counterparts. The structure and function of erythrocytes are strongly modulated by membrane long chain polyunsaturated fatty acids (LCPUFA). We have tested the possibility that HbSC and HbSS patients have different membrane fatty acid composition consistent with the difference in their clinical severity. Steady-state patients, 9 HbSC and 28 HbSS, and 15 HbAA were studied. The HbSC patients had a higher level of linoleic (LA, P<0.05) and docosahexaenoic (DHA, P<0.05) acids, and lower arachidonic acid (AA, P<0.01) and AA/eicosapentaenoic acid (EPA) ratio (P<0.05) in erythrocyte choline phosphoglycerides (CPG) compared with the HbSS group. Similarly, the level of EPA was higher and AA/EPA ratio (P<0.01) lower in serine phosphoglycerides of the HbSC patients. In contrast to the HbSC, the HbSS group had lower levels of EPA (P<0.001), DHA (P<0.05), total n-3 metabolites and total n-3 fatty acids (P<0.001) in erythrocyte CPG compared with the healthy HbAA controls. Moreover, the HbSS patients with disease complications compared with those without complications had reduced DHA and total n-3 fatty acids (P<0.005) in erythrocyte CPG. The abnormalities in erythrocyte in LCPUFA which is manifested by an increase in AA and a decrease in EPA and DHA in HbSS relative to HbSC disease observed in this study are consistent with the contrast in clinical severity between the two entities.

Polyunsaturated fatty acids in plasma lipids of diabetic children during and after diabetic ketoacidosis

BACKGROUND AND AIM

Previously we reported significantly higher plasma values of the essential fatty acids but significantly lower values of their longer-chain metabolites in diabetic children than in healthy controls. Here, we report data on the acute effect of diabetic ketoacidosis (DKA) on the fatty acid composition of plasma lipids.

METHODS

Diabetic children (n=9; age: 16.1 [3.3] y; duration of diabetes: 5.0 [5.3.] y; daily insulin dose: 0.87 [0.66] unit/kg body weight/d; glycated haemoglobin: 13.4 [2.8] %; median [IQR]) were investigated at admission for DKA (during DKA) and at the end of the treatment of DKA (after DKA). Fatty acid composition of plasma lipid classes was determined by high-resolution capillary gas-liquid chromatography.

RESULTS

Blood glucose (27.0 [8.5] vs 6.5 [1.6] mmol/l), pH (7.28 [0.35] vs 7.36 [0.06]) and base excess (-8.9 [15.1] vs -2.2 [6.3] mmol/l) were grossly abnormal during but not after DKA. Values of linoleic acid were significantly lower after than during DKA (non-esterifed fatty acids (NEFA): 15.55 [1.47] vs 12.27 [5.74] % wt/wt; triacylglycerols (TG): 20.84 [9.23] vs 17.40 [5.78]; p<0.05). In contrast, values of gamma-linolenic acid (NEFA: 0.87 [0.54] vs 2.34 [1.85]; p<0.05) and arachidonic acid (TG: 1.37 [0.71] vs 1.74 [0.57]; p<0.05) were significantly lower during than after DKA. The product/substrate ratios for delta-6 desaturation were significantly lower during than after DKA.

CONCLUSION

Successful treatment of diabetic ketoacidosis is associated with a significant increase of long-chain polyunsaturated fatty acid values in blood plasma in diabetic children. This observation suggests that disturbances of essential fatty acid metabolism in diabetic children are related not only to diet but to hypoinsulinaemia as well.