Metabolomic study of altered energy metabolism during global forebrain ischemia and ischemic precoditioning in blood plasma in homocysteine treated rats

Elevated homocysteine (Hcy) level is a well known risk factor for cardiovascular and neuropsychiatric diseases. In this study, we investigated metabolic changes in blood plasma in Hcy-treated rats. In combination with Hcy injections to induce hyperhomocysteinemia-like state, we used an animal model of global cerebral ischemia to investigate metabolic changes after 24 h reperfusion in rats. We also focused on the endogenous phenomenon known as ischemic tolerance induced by the preischemic treatment. The experiments were carried out on blood plasma samples as they are easily available and metabolically reflect the overall changes in injured organism. We observed significant changes in plasma metabolite levels of: pyruvate, citrate, acetate implicating alterations in energy metabolism, and increase in triacylglycerols, arginine and lysine, in Hcy-treated rats compared with naive animals. Ischemic insult with 24 reperfusion in Hcy-treated rats led to increase in plasma lactate, and decrease in plasma glucose, pyruvate, citrate and acetate. Complementary, an increase in ketone body 3-hydroxybutyrate was observed. The plasma metabolites: alanine, lactate, valine, glucose, leucine, isoleucine, acetate, citrate and 3-hydroxybutyrate were considered to reflect the response induced by ischemic preconditioning in Hcy rats, where the extent of postischemic damage was not as high as in the non-preconditioned rats. Our results provide evidence that nuclear magnetic resonance (NMR) spectra analysis can identify a specific group of metabolites present in plasma with the capability of discriminating between individual groups of animals. Regarding the effect of elevated Hcy level on plasma metabolome, we showed, that acetate, pyruvate and glucose had the excellent discriminatory power between Hcy-treated and naive rats plasma. Concerning ischemic insult in Hcy-treated animals, we also document the ideal discrimination of ischemic from non-ischemic rats by various groups of metabolites, that can be considered as a potential plasma biomarkers.

The age at onset in Multiple Sclerosis is associated with patient's prognosis

BACKGROUND

The causes of the individual differences in the rate of disability progression in multiple sclerosis (MS) are still not completely clear. According to the long-term prognosis of MS patients, the search for new valuable prognostic markers of "benign" or "malign" MS is necessary.

OBJECTIVES

Our aim was to assess the possible association of MS onset age with the disease disability progression rate in Slovak patients with MS.

METHODS

By the unique pattern of evaluation of disability progression rate using Multiple Sclerosis Severity Score (MSSS), each of 270 MS patients was defined as slow-progressing, mid-rate progressing or rapidly progressing.

RESULTS

We found a significant differences in the age at onset between MS patients with different rate of disability progression (p(K-W)<0,00005). The faster was a disability progression assessed by MSSS score, the higher was the MS onset age.

CONCLUSION

We showed for the first time in Central European Slovak population that MS onset age is an early marker that is in the positive correlation with disease disability progression rate, evaluated by MSSS score. We conclude that relapsing-remitting MS patients older at clinical onset have a higher risk of unfavorable prognosis (Tab. 2, Fig. 1, Ref. 21).

Combination of hyperhomocysteinemia and ischemic tolerance in experimental model of global ischemia in rats

Epidemiological studies show positive relationship between mild-to-moderate hyperhomocysteinemia (hHcy) and the risk of cerebrovascular diseases. The study determines whether hyperhomocysteinemia (risk factor of brain ischemia) alone or in combination with the ischemic preconditioning (IPC) affects the ischemia-induced neurodegenerative changes and imbalance in MAPK/p-ERK1/2 and MAPK/p-p38 expression in the rat brains. hHcy was induced by subcutaneous administration of homocysteine (0.45 μmol/g body weight) twice a day at 8 h intervals for 14 days. Rats were preconditioned by 5 min ischemia and 2 days later, 15 min of global forebrain ischemia was induced by four vessel occlusion. We observed that hHcy alone significantly increased neurodegeneration by Fluoro-Jade C and TUNEL possitive cells in hippocampus as well as in cortex. We found elevated level of MAPK/p-ERK and decreased level of MAPK/p-p38 after pre-ischemic challenge by Western blot and fluorescent immunohistochemistry. In conclusion, preconditioning even if combined with hHcy could preserve the neuronal tissue from lethal ischemic effect. This study provides evidence for the interplay and tight integration between ERK and p38 MAPKs signalling mechanisms in response to the hHcy and also if in association with brain ischemia/IPC challenge in the rat brain.

p-ERK involvement in the neuroprotection exerted by ischemic preconditioning in rat hippocampus subjected to four vessel occlusion

Global brain ischemia-reperfusion causes delayed cell death in hippocampal CA1 (cornus ammonis 1) pyramidal neurons after reperfusion. Ischemic tolerance evoked by preconditioning (IPC) represents a phenomenon of CNS adaptation to any subsequent ischemia. This paper was designed to describe changes in the mitogen-activated protein kinases (MAPK) protein pathways of the hippocampal area following by IPC. Ischemia was induced by a 4-vessels occlusion (4VO) and the rats were preconditioned by a non-injurious ischemia. Apoptotic markers were used to follow the degeneration process. Western blot and immunohistochemistry identified p-ERK (phosphorylated extracellular signal-regulated protein kinase) and p38 proteins in injured hippocampal areas. P-ERK quantification increased after IPC and reached the highest level at 24 hours after ischemia. Interestingly, neuroprotection induced by IPC lead to the opposite effect on MAPK/p38, where the level was lowest at 24 hours after ischemia. Taken together, the present study clearly demonstrates that p-ERK takes part in complex cascades triggered by IPC in the selectively vulnerable hippocampal region. In addition, paper describes a crosstalk between p-ERK and p-p38 which occurs after preconditioning maneuver in 4VO model of global ischemia.

Hyperhomocysteinemia as a risk factor for the neuronal system disorders

Elevated concentration of the homocysteine (Hcy) in human tissues, resulting either from mutations in genes enconding Hcy-metabolizing enzymes, or from deficiences of folic acid has recognized cytotoxic effect. Even a mild Hcy level increase is a risk factor for cardiovascular diseases and stroke in humans and also a risk factor for neurodegenerative disordes, such as dementia, or Alzheimer's disease. However, it is not yet clear whether homocysteine is a marker, or a causative agent. We present here an overview of recent data on the homocysteine metabolism and on the genetic and the metabolic causes of hyperhomocysteinemia-related pathologies in humans. In context of our results which detected an increased oxidative stress in hyperhomocysteinemic rats we discuss here the role of free radicals in this disorder. Imbalance between homocysteine auto-oxidation, production of reactive metabolites and cellular antioxidant defence induced by hyperhomocysteinemia results to cytotoxicity by oxidizing membrane lipids and proteins. Consequently, protein thiolation and homocysteinylation results in the structural and functional modifications of cells, including neuronal ones. It is our hope that identification of prophylacting factors effective in the prevention of toxic effect of Hcy would lead to improved therapeutics, especially the brain tissue.

Effects of long-term oxygen treatment on alpha-ketoglutarate dehydrogenase activity and oxidative modifications in mitochondria of the guinea pig heart

OBJECTIVE

Oxygen therapy is used for the treatment of various diseases, but prolonged exposure to high concentrations of O(2) is also associated with formation of free radicals and oxidative damage.

METHODS

In the present study we compared alpha-ketoglutarate dehydrogenase (KGDH) activity and mitochondrial oxidative damage in the hearts of guinea pigs after long-term (17 and 60 h) oxygenation with 100% normobaric O(2) and with partially negatively (O(2 neg)) or positively (O(2 posit)) ionized oxygen.

RESULTS

Inhalation of O(2) led to significant loss in KGDH activity and thiol group content and accumulation of bityrosines. Inhalation of O(2 neg) was accompanied by more pronounced KGDH inhibition, possibly due to additional formation of protein-lipid conjugates. In contrast, O(2 posit) prevented loss in KGDH activity and diminished mitochondrial oxidative damage.

CONCLUSIONS

These findings suggest that oxygen treatment is associated with impairment of heart energy metabolism and support the view that inhalation of O(2 posit) optimizes the beneficial effects of oxygen therapy.

Effect of aging on the expression of intracellular Ca(2+) transport proteins in a rat heart

Aging process is accompanied by various biological dysfunctions including altered calcium homeostasis. Modified calcium handling might be responsible for changed cardiac function and potential development of the pathological state. In the present study we compared the mRNA and protein levels of the intracellular Ca(2+)-handling proteins--inositol 1,4,5-trisphosphate receptor (IP(3)R), ryanodine receptor (RyR), sarcoplasmic reticulum Ca(2+) pump (SERCA2), and also transient receptor potential C (TRPC) channels in cardiac tissues of 5-, 15-, and 26-month-old rats. Aging was accompanied by significant increase in the mRNA levels of IP(3)R and TRPC channels in both ventricles and atria, but mRNA level of the type 2 RyR was unchanged. Protein content of the IP(3)R1 correlated with mRNA levels, in the left ventricle of 15- and 26-month-old rats the value was approximately 1.8 and 2.8-times higher compared to 5-month-old rats. No significant differences were observed in mRNA and protein levels of the SERCA2 among 5-month-old and aged rats. However, Ca(2+)-ATPase activity significantly decreased with age, activities in 5-, 15-, and 26-month-old rats were 421.2 +/- 13.7, 335.5 +/- 18.1 and 304.6 +/- 14.8 nmol P(i) min(-1) mg(-1). These results suggest that altered transporting activity and/or gene expression of Ca(2+)-handling proteins of intracellular Ca(2+) stores might affect cardiac function during aging.

Biochemical and clinical improvement of cytotoxic state by amantadine sulphate

1. The main idea of the open clinical trial was to compare the income and outcome clinical picture and the evolution of the biochemical markers in the defined intervals in closed head injury group patients. 2. In the group of 32 patients, mean age 40.78+/-15.36 years suffering from closed traumatic brain injury the following markers were measured: glycaemia, malondialdehyde (MDA) as marker of lipid peroxidation, beta-caroten, total SH groups as marker of protein oxidation in the following intervals: between the 1st and the 3rd, between the 3rd and the 7th, between the 1st and the 7th day respectively. 3. Glycaemia significantly decreased since the 1st day till the 3rd day (p < 0.05) and since the 1st day till the 7th day (p < 0.05) but it was not significantly changed since the 3rd day till the 7th day (p > 0.05). 4. MDA 1st x MDA 3rd p > 0.05 insignificant change, MDA 1st x MDA 7th p < 0.001--high significant decrease, MDA 3rd x MDA 7th--p < 0.0001--very high significant decrease. 5. Beta-caroten the 1st x beta-caroten the 3rd day was insignificantly changed-p > 0.05, the 3rd x the 7th day beta-caroten increased significantly--p < 0.0002, the 1st day x 7th day beta-caroten significantly increased--p < 0.0001. 6. We examined the SH groups only in nine patients, due to technical problems and SH groups decrease on the 3rd day (p < 0.005). 7. In 18 amantadine sulphate subgroups (randomly selected), there was 5.5% lethality and mean outcome GCS (outGCS) 9.83+/-3.8, while lethality of the control subgroup (n=14) was 42.9%, mean outGCS 6.28+/-3.5.

Stimulation of the catalytic cycle of the Ca2+ pump of porcine plasma-membranes by negatively charged phospholipids

The (Ca(2+)+Mg2+)-ATPase of the plasma membrane is activated by negatively charged phospholipids. The mechanism of this activation was investigated by studying the effect of negatively charged phospholipids on the steady-state phosphointermediate level and on the p-nitrophenylphosphatase activity. Both parameters were differentially affected by different acidic phospholipids. The level of phosphoprotein intermediate was not affected by phosphatidylserine (20% of total phospholipid), but it was increased by 60% by phosphatidylinositol 4-phosphate. Phosphatidylserine increased the p-nitrophenylphosphatase activity, whereas phosphatidylinositol 4-phosphate had no significant effect. It is suggested that phosphatidylinositol 4-phosphate mainly affects a reaction step which leads to accelerated formation of the phosphointermediate, whereas the action of phosphatidylserine would affect two reaction steps, one upstream and one downstream of the phosphointermediate.

Conformational changes of (Ca2+-Mg2+)-ATPase of erythrocyte plasma membrane caused by calmodulin and phosphatidylserine as revealed by circular dichroism and fluorescence studies

Two spectroscopic techniques, circular dichroism and steady-state fluorescence, were employed in order to study conformational changes of the purified, detergent-solubilized (Ca2+-Mg2+)-ATPase of porcine erythrocyte ghost membranes. Circular dichroism (CD) spectra in the peptide region were obtained from the purified (Ca2+-Mg2+)-ATPase of porcine erythrocyte ghost membranes with the aim to investigate the secondary structure of the enzyme in the presence of calmodulin (CaM) or phosphatidylserine (PS), as well as in the E1 and E2 states. The E1 conformation was stabilized by 10 microM free Ca2+, while the E2 conformation was stabilized by 0.1 mM ethylene glycol bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). It was found that the E1 and E2 states of the enzyme strikingly differed in their secondary structure (66% and 46% of calculated alpha-helix content, respectively). In the presence of Ca2+, PS decreased the helical content of the ATPase to 61%, while CaM to 55%. Quenching of intrinsic fluorescence of (Ca2+-Mg2+)-ATPase by acrylamide, performed in the presence of Ca2+, gave evidence for a single class of tryptophan residues with Stern-Volmer constant (KSV) of 10 M-1. Accessibility of tryptophan residues varied depending on the conformational status of the enzyme. Addition of PS and CaM decreased the KSV value to 7.6 M-1 and 8.5 M-1, respectively. In the absence of Ca2+, KSV was 7.0 M-1. KI and CsCl were less effective as quenchers. The fluorescence energy transfer between (Ca2+-Mg2+)-ATPase tryptophan residues and dansyl derivative of covalently labeled CaM occurred in the presence of EGTA, but was further promoted by Ca2+. It is concluded that the interaction of CaM and PS with (Ca2+-Mg2+)-ATPase results in different conformational states of the enzyme. CD and fluorescence spectroscopy allowed to distinguish these states from the E1 and E2 conformational forms of the ATPase.