The immiscible cholesterol bilayer domain exists as an integral part of phospholipid bilayer membranes

Electron paramagnetic resonance (EPR) spin-labeling methods were used to study the organization of cholesterol and phospholipids in membranes formed from Chol/POPS (cholesterol/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylserine) mixtures, with mixing ratios from 0 to 3. It was confirmed using the discrimination by oxygen transport and polar relaxation agent accessibility methods that the immiscible cholesterol bilayer domain (CBD) was present in all of the suspensions when the mixing ratio exceeded the cholesterol solubility threshold (CST) in the POPS membrane. The behavior of phospholipid molecules was monitored with phospholipid analogue spin labels (n-PCs), and the behavior of cholesterol was monitored with the cholesterol analogue spin labels CSL and ASL. Results indicated that phospholipid and cholesterol mixtures can form a membrane suspension up to a mixing ratio of ~2. Additionally, EPR spectra for n-PC, ASL, and CSL indicated that both phospholipids and cholesterol exist in these suspensions in the lipid-bilayer-like structures. EPR spectral characteristics of n-PCs (spin labels located in the phospholipid cholesterol bilayer, outside the CBD) change with increase in the cholesterol content up to and beyond the CST. These results present strong evidence that the CBD forms an integral part of the phospholipid bilayer when formed from a Chol/POPS mixture up to a mixing ratio of ~2. Interestingly, CSL in cholesterol alone (without phospholipids) when suspended in buffer does not detect formation of bilayer-like structures. A broad, single-line EPR signal is given, similar to that obtained for the dry film of cholesterol before addition of the buffer. This broad, single-line signal is also observed in suspensions formed for Chol/POPS mixtures (as a background signal) when the Chol/POPS ratio is much greater than 3. It is suggested that the EPR spin-labeling approach can discriminate and characterize the fraction of cholesterol that forms the CBD within the phospholipid bilayer.     

IGFs and IGF-Binding Proteins in the Synovial Fluid of Patients with Rheumatoid Arthritis and Osteoarthritis

International Journal of Peptide Research and Therapeutics - The progressive damage of human articular cartilage is associated with loss of integrity of its extracellular matrix components. Their...     

SOD-Like Activity of Copper(II) Containing Metallopeptides Branched By 2,3-Diaminopropionic Acid: What the N-Termini Elevate,the C-Terminus Ruins

International Journal of Peptide Research and Therapeutics - Relations between structural modifiactions and SOD-like activity of four branched CuII-metallopeptides based on l-2,3-diaminopropionic...     

Antihypertensive mechanism of the dipeptide Val-Tyr in rat aorta

Antihypertensive peptides received much interest over the last decade. These peptides are known to be angiotensin converting enzyme (ACE) inhibitors in vitro, but the actual antihypertensive mechanisms in vivo are still unclear. In this research, we used rat aortic rings in organ bath experiments to investigate five potential vascular antihypertensive mechanisms of the dipeptide Val-Tyr. Only one significant effect was observed, namely preincubation of the aorta with Val-Tyr led to a significant shift of the concentration-response curve evoked by angiotensin I (Ang I). Val-Tyr had no effect on the angiotensin II receptor or the alpha-adrenergic receptor. Furthermore, it did not interact with voltage-operated Ca2+ channels, or with nitric oxide production/availability. In conclusion, our results show that Val-Tyr specifically inhibits Ang I-evoked contraction through ACE inhibition and that four other main mechanisms of vascular tone regulation are not affected.     

Gender-Specific Effects of Depression and Suicidal Ideation in Prosocial Behaviors

Background

Prosocial behaviors are essential to the ability to relate to others. Women typically display greater prosocial behavior than men. The impact of depression on prosocial behaviors and how gender interacts with those effects are not fully understood. We explored the role of gender in the potential effects of depression on prosocial behavior.

Methods

We examined prosocial behaviors using a modified version of the Trust Game in a clinical population and community controls. Study participants were characterized on the severity of depression and anxiety, presence of suicidal ideation, history of childhood trauma, recent stressful life events, and impulsivity. We correlated behavioral outcomes with gender and clinical variables using analysis of variance and multiple regression analysis.

Results

The 89 participants comprised four study groups: depressed women, depressed men, healthy women and healthy men (n = 16–36). Depressed men exhibited reciprocity more frequently than healthy men. Depression induced an inversion of the gender-specific pattern of self-centered behavior. Suicidal ideation was associated with increased reciprocity behavior in both genders, and enhancement of the effect of depression on gender-specific self-centered behavior.

Conclusions

Depression, particularly suicidal ideation, is associated with reversal of gender-specific patterns of prosocial behavior, suggesting abnormalities in sexual hormones regulation. This explanation is supported by known abnormalities in the hypothalamus-pituitary-adrenal and hypothalamus-pituitary-gonadal axes found in depression.     

Prognostic Value of Malic Enzyme and ATP-Citrate Lyase in Non-Small Cell Lung Cancer of the Young and the Elderly

Background

Lung cancer is the leading cause of death among malignancies worldwide. Understanding its biology is therefore of pivotal importance to improve patient’s prognosis. In contrast to non-neoplastic tissues, cancer cells utilize glucose mainly for production of basic cellular modules ‘(i.e. nucleotides, aminoacids, fatty acids). In cancer, Malic enzyme (ME) and ATP-citrate lyase (ACLY) are key enzymes linking aerobic glycolysis and fatty acid synthesis and may therefore be of biological and prognostic significance in non-small cell lung cancer (NSCLC).

Material and Methods

ME and ACLY expression was analyzed in 258 NSCLC in correlation with clinico-pathological parameters including patient’s survival.

Results

Though, overall expression of both enzymes correlated positively, ACLY was associated with local tumor stage, whereas ME correlated with occurrence of mediastinal lymph node metastases. Young patients overexpressing ACLY and/or ME had a significantly longer overall survival. This proved to be an independent prognostic factor. This contrasts older NSCLC patients, in whom overexpression of ACLY and/or ME appears to predict the opposite.

Conclusion

In NSCLC, ME and ACLY show different enzyme expressions relating to local and mediastinal spread. Most important, we detected an inverse prognostic impact of ACLY and/or ME overexpression in young and elderly patients. It can therefore be expected, that treatment of NSCLC especially, if targeting metabolic pathways, requires different strategies in different age groups.     

Changes in antioxidant status of heart muscle tissue in experimental diabetes in rabbits

The present study was designed to evaluate the oxidative stress-related parameters in alloxan-induced diabetes in rabbits. After 3, 6, 12 and 24 weeks of hyperglycaemia the enzymatic and non-enzymatic factors were measured in heart tissue of diabetic and control groups. Superoxide dismutase and glutathione peroxidase activities and the contents of total sulfhydryl compounds significantly increased at all time intervals. Catalase activity increased initially (after 3 and 6 weeks), decreased after 12 weeks and increased again at the 24th week of the experiment. Glutathione reductase activity increased initially (at 3rd week), decreased below control level after 6 and 12 weeks, then increased again. Ascorbic acid concentration decreased after 3 and 6 weeks, and increased at the 12th and 24th weeks. The level of lipid peroxidation products was reduced after 3, 6 and 12 weeks of the experiment. After 24 weeks it was significantly elevated. These data suggest that hyperglycaemia induces oxidative stress in the heart but the defense mechanisms in the heart tissue are fairly efficacious against oxidative injury.     

Binding abilities of dehydropeptides towards Cu(II) and Ni(II) ions. Impact of Z-E isomerization on metal ion binding

The study on the binding ability of dehydro-tri- and tetrapeptides has shown that the ,β-double bond has a critical effect on the peptide coordination to metal ions. It may affect the binding of the vicinal amide nitrogens by the electronic effect and stabilize the complex due to steric effects. The (Z) isomer is the most effective in stabilizing of the complexes formed. The presence of large side chain in the dehydroamino acid residue may also be critical for the coordination mode in the metallopeptide systems.