Leucocyte glutathione peroxidase activity and selenium level in multiple sclerosis

Exploring the Relationship between Antioxidant Enzymes, Oxidative Stress Markers, and Clinical Profile in Relapsing-Remitting Multiple Sclerosis

We aimed to investigate the extent of alterations in the pro/antioxidant balance in the blood of patients with relapsing-remitting multiple sclerosis (RRMS) in relation to drug-modified therapy, gender, disability score, and disease duration. 161 patients (67 men and 94 women, aged 24-69 years, median 43.0) and 29 healthy individuals (9 men and 20 women, aged 25-68 years, median 41.0) were included in the study. We measured the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) as well as the concentration of interleukin-6 (IL-6), lipid peroxidation parameters (LPO), total oxidant status (TOS), and total antioxidant capacity (TAS). The activity of SOD did not show any significant differences between patients with RRMS and the control group in our study. In contrast, significant decreased GPx activity and increased CAT activity was observed in the blood of patients with RRMS compared to the control group. Additionally, the activity of CAT was influenced by gender and the use of disease-modifying therapies. Disease-modifying therapies also affected the concentration of TOS, TAS, and LPO. Our studies indicated that enhancing GPx activity may be more beneficial to providing potential therapeutic strategies aimed at modulating antioxidant defenses to mitigate oxidative stress in this disease.

Blood Trace Element Status in Multiple Sclerosis: a Systematic Review and Meta-analysis

The aim of this meta-analysis was to investigate whether the blood concentrations of patients with multiple sclerosis (MS) are associated with those of the healthy control group in terms of trace elements including zinc (Zn), iron (Fe), manganese (Mn), magnesium (Mg), selenium (Se), and copper (Cu). A comprehensive search was performed in online databases including PubMed, Scopus, Embase, and Web of Science for studies, which have addressed trace elements in MS up to July 23, 2020. The chi-square test and I² statistic were utilized to evaluate inter-study heterogeneity across the included studies. Weighted mean differences (WMDs) and corresponding 95% CI were considered as a pooled effect size (ES). Twenty-seven articles (or 32 studies) with a total sample comprised of 2895 participants (MS patients (n = 1567) and controls (n = 1328)) were included. Pooled results using random-effects model indicated that the levels of Zn (WMD = - 7.83 mcg/dl, 95% CI = - 12.78 to - 2.87, Z = 3.09, P = 0.002), and Fe (WMD = - 13.66 mcg/dl, 95% CI = - 23.13 to - 4.19, Z = 2.83, P = 0.005) were significantly lower in MS patients than in controls. However, it was found that levels of Mn (WMD = 0.03 mcg/dl, 95% CI = 0.01 to 0.04, Z = 2.89, P = 0.004) were significantly higher in MS patients. Yet, no significant differences were observed in the levels of Mg, Se, and Cu between both groups. This meta-analysis revealed that the circulating levels of Zn and Fe were significantly lower in MS patients and that Mn level was significantly higher than those in the control group. However, it was found that there was no significant difference between MS patients and controls with regard to levels of Mg, Se, and Cu.

Monitoring the Redox Status in Multiple Sclerosis

Worldwide, over 2.2 million people suffer from multiple sclerosis (MS), a multifactorial demyelinating disease of the central nervous system. MS is characterized by a wide range of motor, autonomic, and psychobehavioral symptoms, including depression, anxiety, and dementia. The blood, cerebrospinal fluid, and postmortem brain samples of MS patients provide evidence on the disturbance of reduction-oxidation (redox) homeostasis, such as the alterations of oxidative and antioxidative enzyme activities and the presence of degradation products. This review article discusses the components of redox homeostasis, including reactive chemical species, oxidative enzymes, antioxidative enzymes, and degradation products. The reactive chemical species cover frequently discussed reactive oxygen/nitrogen species, infrequently featured reactive chemicals such as sulfur, carbonyl, halogen, selenium, and nucleophilic species that potentially act as reductive, as well as pro-oxidative stressors. The antioxidative enzyme systems cover the nuclear factor erythroid-2-related factor 2 (NRF2)-Kelch-like ECH-associated protein 1 (KEAP1) signaling pathway. The NRF2 and other transcriptional factors potentially become a biomarker sensitive to the initial phase of oxidative stress. Altered components of the redox homeostasis in MS were discussed in search of a diagnostic, prognostic, predictive, and/or therapeutic biomarker. Finally, monitoring the battery of reactive chemical species, oxidative enzymes, antioxidative enzymes, and degradation products helps to evaluate the redox status of MS patients to expedite the building of personalized treatment plans for the sake of a better quality of life.

Potential Role of Trace Elements (Al, Cu, Zn, and Se) in Multiple Sclerosis Physiopathology

Multiple sclerosis (MS) is an unpredictable disease of the central nervous system. The cause of MS is not known completely, and pathology is specified by involved demyelinated areas in the white and gray matter of the brain and spinal cord. Inflammation and peripheral tolerance breakdown due to Treg cell defects and/or effector cell resistance are present at all stages of the disease. Several invading peripheral immune cells are included in the process of the disease such as macrophages, CD8+ T cells, CD4+ T cells, B cells, and plasma cells. Trace elements are known as elements found in soil, plants, and living organisms in small quantities. Some of them (e.g., Al, Cu, Zn, Mn, and Se) are essential for the body's functions like catalysts in enzyme systems, energy metabolism, etc. Al toxicity and Cu, Zn, and Se toxicity and deficiency can affect the immune system and following neuron inflammation and degeneration. These processes may result in MS pathology. Of course, factors such as lifestyle, environment, and industrialization can affect levels of trace elements in the human body.

Oxidative stress-related biomarkers in multiple sclerosis: a review

AIM

To provide an up-to-date review of oxidative stress biomarkers in multiple sclerosis and thus identify candidate molecules with greatest promise as biomarkers of diagnosis, disease activity or prognosis.

METHOD

A semi-systematic literature search using PubMed and other databases.

RESULTS

Nitric oxide metabolites, superoxide dismutase, catalase, glutathione reductase, inducible nitric oxide synthase, protein carbonyl, 3-nitrotyrosine, isoprostanes, malondialdehyde and products of DNA oxidation have been identified across multiple studies as having promise as diagnostic, therapeutic or prognostic markers in MS.

CONCLUSION

Heterogeneity of study design, particularly patient selection, limits comparability across studies. Further cohort studies are needed, and we would recommend promising markers be incorporated into future clinical trials to prospectively validate their potential.

Glutathione in multiple sclerosis: More than just an antioxidant?

Oxidative stress has been strongly implicated in both the inflammatory and neurodegenerative pathological mechanisms in multiple sclerosis (MS). In response to oxidative stress, cells increase and activate their cellular antioxidant mechanisms. Glutathione (GSH) is the major antioxidant in the brain, and as such plays a pivotal role in the detoxification of reactive oxidants. Previous research has shown that GSH homeostasis is altered in MS. In this review, we provide a comprehensive overview on GSH metabolism in brain cells, with a focus on its involvement in MS. The potential of GSH as an in vivo biomarker in MS is discussed, along with a short overview of improvements in imaging methods that allow non-invasive quantification of GSH in the brain. These methods might be instrumental in providing real-time measures of GSH, allowing the assessment of the oxidative state in MS patients and the monitoring of disease progression. Finally, the therapeutic potential of GSH in MS is discussed.

Peroxidation of lipoproteins in multiple sclerosis

Human plasma low density lipoproteins (LDL) and high density lipoproteins (HDL) are involved in the transport of lipids, modulate membrane lipid composition and regulate signal transduction. HDL-like lipoproteins have been shown also in human cerebrospinal fluid and it has been hypothesized that they could have a role in lipid transport in central nervous system. After synthesis, lipoproteins are susceptible to lipid peroxidation triggered by reactive oxygen species (ROS and RNS) produced by peripheral and brain cells. Aim of the paper has been to review the scientific literature on the role of lipid peroxidation of LDL and HDL in the molecular mechanisms of multiple sclerosis (MS). Several studies have demonstrated a significant increase in lipid peroxidation products in brain, plasma and cerebrospinal fluid of MS patients. The increase of antibodies against ox-LDL in plasma and the presence of ox-LDL in demyelinating plaques in MS brain suggests that the disease is associated with oxidative damage of lipoproteins. The impairment of antioxidant systems or an increase in the production of ROS and RNS could contribute to lipoprotein peroxidation in MS. Oxidized lipoproteins show several alterations of their functions, they are neurotoxic and have pro-inflammatory properties. Therefore lipoprotein lipid peroxidation products could be involved in demyelination and axonal injury in MS.

Intracellular oxidative activity and respiratory burst of leukocytes isolated from multiple sclerosis patients

Oxidative damage induced by free radicals and reactive oxygen species (ROS) have been suggested to play an important role in the development of autoimmune diseases such as multiple sclerosis (MS) disease and it has been hypothesised that oxidative injury could mediate demyelination and axonal injury in MS subjects. In our study, we compared intracellular oxidative activity and the respiratory burst activity in MS patients (n=20) and healthy controls (n=15) using leukocytes as cellular model. At this purpose, intracellular ROS levels were evaluated by fluorometric assay using the 2'-7'-dichlorodihydrofluorescin diacetate probe (H(2)DCFDA) in untreated or in leukocytes stimulated with phorbol-12-myristate-13-acetate (PMA). Our results demonstrate that the intracellular spontaneous ROS production in leukocytes from MS patients was higher with respect to cells from control subjects (p<0.001). PMA addition induced a higher formation of ROS both in leukocytes from MS patients and controls (p<0.001). The PMA-induced production of ROS was significantly higher in leukocytes from MS with respect to controls (p<0.001). Significant positive correlations were established between intracellular spontaneous or PMA-induced production of ROS in leukocytes isolated from MS patients and the clinical parameters used to evaluate disease disability such as expanded disability status scale (EDSS), brain lesions evaluated by MRI and visual evoked potential (VEP) (p<0.001). In conclusion, our results demonstrate higher levels of intracellular ROS in untreated or in PMA-treated leukocytes isolated from MS patients with respect to healthy subjects confirming the role of oxidative stress in multiple sclerosis.

Multiple sclerosis and nutrition

Benefits from any particular diet in multiple sclerosis (MS) have not yet been proven. It is, however, frequent that malnutrition may potentially exacerbate the symptoms of MS. There is some evidence that a high intake of saturated fat increases the incidence of MS. Epidemiological studies imply that unsaturated fatty acids may have a positive effect on the course of MS. However, the results of controlled studies are ambiguous. A meta-analysis of three small controlled clinical trials suggests a benefit from linoleic acid. Intake of Vitamin D is associated with a lower incidence of MS. In MS, the risk of osteoporosis is high, and prophylactic vitamin D and calcium should be considered at an early stage. The role of minerals, trace elements, antioxidants, vitamins or fish oil is unclear. The possible relationships between diet and MS have not been subjected to adequate study. It seems possible that in the future, diets or dietary supplements may become recommended forms of treatment for MS.

[Diet and multiple sclerosis]

Beneficial effects from any particular diet have not been proven in multiple sclerosis (MS). Therefore, the general guidelines on nutrition should be followed. Obesity and various forms of malnutrition worsening the MS symptoms are frequently observed. There is some evidence from epidemiological studies that a high consumption of saturated animal fat is associated with an increased incidence of MS. The findings from such studies indicate that supplementation with unsaturated fatty acids, in particular omega-3 fatty acids, could positively influence the course of MS. However, controlled studies did not show clear beneficial effects from polyunsaturated fatty acids. The intake of vitamin D is associated with a lower incidence of MS. In contrast, the effects of therapy with vitamin D on the course of MS have not been ascertained. Patients with MS carry an enormous risk of osteoporosis, and therefore the indication for a preventive therapy with vitamin D and calcium should be established in every postmenopausal woman or after repeated steroid treatments.

Lymphocyte glutathione peroxidase activity during exacerbations in multiple sclerosis

Glutathione peroxidase, one of the major antioxidants in the human brain, has been found to have decreased activity in patients suffering from multiple sclerosis (MS). This study compares the activity of lymphocyte glutathione peroxidase (L-GSH-px) in MS patients suffering from acute relapses with clinically stable MS patients and with control patients referred with nondemyelinating neurological diseases. All three groups showed an increase of mean enzymatic activity (MEA) during the observation period. The highest MEA in this study was observed in the MS groups. However, there were no significant differences in the L-GSH-px activity in the three groups. These results are not in accordance with previous investigations, and the need for further research in this field is emphasized.

High dose antioxidant supplementation to MS patients. Effects on glutathione peroxidase, clinical safety, and absorption of selenium

High-dose antioxidant supplementation has recently been recommended for multiple sclerosis (MS) patients. This study tests the clinical safety, the glutathione peroxidase (GSH-px) activity, and the absorption of selenium during such supplementation. Eighteen MS patients were given 6 tablets especially made for this study, equivalent to 6 mg sodium selenite, 2 g vitamin C, and 480 mg vitamin E a day for five wk. GSH-px, which was lower than in non-MS controls before the start of treatment, increased fivefold during 5 wk of treatment. Side effects were scarce. Ten MS patients were subjected to a 24-h selenium absorption study after ingestion of 2 active tablets, equivalent to 2 mg sodium selenite. Selenium, which was low initially, increased 24% during the first 3 h and then stabilized. It is concluded that the tested antioxidant treatment seems to be safe and that MS patients have low GSH-px, which may be increased by the tested antioxidant treatment.

Serum selenium concentration, glutathione peroxidase activity and lipid peroxides in a co-twin control study on multiple sclerosis

Serum selenium concentration, glutathione peroxidase activity and lipid peroxides were determined in patients with multiple sclerosis (MS). The series consisted of 13 same-sexed twin pairs derived from the Finnish Twin Cohort of 15,815 pairs. Fourteen subjects had a definite and 1 a probable MS, and their 11 co-twins showed no evidence of central nervous system disease. No statistical differences were observed, but the 3 patients with active progressive MS had a higher mean level of lipid peroxides than the rest of the patients. We suggest that serum lipid peroxidation may be involved in the activity of MS.

Selenium: clinical significance and analytical concepts

Selenium is an essential trace element in humans and animals. Its only established function in humans is the antioxidant activity of glutathione peroxidase, a selenoenzyme. Severe prolonged deficiency may cause a fatal cardiomyopathy. Iatrogenic causes of selenium deficiency include parenteral and enteral nutrition. Low plasma selenium is also found in malabsorption, cystic fibrosis, rheumatoid arthritis, neoplasia, and other varied clinical disorders. Death has resulted from a single massive ingestion of selenium, while chronic excessive intake causes skin, nail, and hair pathology. Extreme geographical variation in population blood and urine selenium levels and a marked age-specific variation in population reference intervals are important factors in understanding selenium nutrition. Nutritional requirements, biological availability, and metabolism are discussed in relation to geographical, age, and method variability. Sampling, processing procedures, and methods for selenium quantitation are reviewed. Selenium content in different biological matrices and reference values for pediatric, adult, and obstetric populations are provided.

25-Hydroxycholesterol promotes myelin basic protein-induced leakage of phospholipid vesicles

Among several cholesterol oxidation products, 25-hydroxycholesterol is particularly potent in enhancing basic protein-induced carboxyfluorescence leakage from liposomes. Both myelin basic protein and poly(L-arginine) are effective at submicromolar concentrations in stimulating this vesicle rupture. Leakage is greatly augmented by the presence of only 1% of the 25-hydroxycholesterol. The possible relevance of these findings to myelin pathology is discussed.

Lipid peroxidation products and antioxidant proteins in plasma and cerebrospinal fluid from multiple sclerosis patients

Lipid peroxidation (LPx) products were measured as thiobarbituric acid-reactive substances (TS) and lipid-soluble fluorescent pigments (FP) in both plasma and CSF from MS patients and controls. Although no significant changes were found in MS plasma, we report here for the first time increases in both TS and FP in MS CSF (p less than 0.05 and p less than 0.01, respectively, compared with patients with other neurological diseases), indicating that increased LPx in CNS may be a feature of MS. Levels of transferrin were normal but caeruloplasmin (CP), a major antioxidant plasma protein, was significantly raised in MS patients (p less than 0.01) and this may represent an adaptive response to increased oxidative challenge. Neither of these proteins was detectable in CSF using radial immunodiffusion. There was no significant correlation between the severity or duration of the disease nor the period since the last relapse and either LPx products or CP suggesting that the changes observed in this work are not simply the direct result of demyelination and tissue damage.

Selenium status in vegans and lactovegetarians

Plasma and urinary selenium were determined among vegans, lactovegetarians and several groups of omnivorous subjects, using gas-liquid chromatography. Plasma Se was lower among lactovegetarians (0.80 (SD 0.18) mumol/l) than in the other groups (0.98 (SD 0.15) mumol/l). This was not related to Se intake, since the vegans had a lower and the lactovegetarians a higher intake of Se than omnivorous subjects in Sweden. Urinary Se was 0.36 (SD 0.10) mumol/d for controls, 0.17 (SD 0.10) mumol/d for vegans and 0.16 (SD 0.07) mumol/d for lactovegetarians. No relation between dietary Se and urinary Se was observed. Among vegetarians, plasma Se and urinary Se were correlated (r 0.51; P less than 0.05).

Abnormalities of serum and plasma components in patients with multiple sclerosis

Qualitative and quantitative abnormalities in protein and non-protein components of serum and plasma in patients with multiple sclerosis have been the subjects of numerous reports. In this review many of the more recent observations are documented and evaluated. It is concluded that at present the welter of information that has been gathered does not contribute in any major, coherent way to our understanding of the etiology or pathogenesis of the disorder. Several of the abnormalities that have been observed may be future candidates for biochemical markers for multiple sclerosis; at present none is sufficiently reliable, distinctive or easily performed to warrant the status of a useful diagnostic or prognostic test.

Trace elements in human body fluids and tissues

Published figures for trace element concentrations in body fluids and tissues of apparently healthy subjects are widely divergent. For a considerable time, the apparent disparities were readily ascribed to biological sources of variation such as age, sex, dietary habits, physiological conditions, environmental exposure, geographical circumstances, or similar influences. Growing evidence, however, suggests that this interpretation may be seriously questioned in numerous instances. First, values obtained in reference materials leave no doubt that some previous studies must have been subject to gross analytical inaccuracies. Second, it has now been thoroughly documented that inadequate sample collection and manipulation may drastically distort the intrinsic trace element content of biological matrices. This review scrutinizes data reported by a number of investigators. In an effort to settle the currently flourishing confusion, critically selected reference values are set forth for trace element levels in human blood plasma or serum, packed blood cells, urine, lung, liver, kidney, and skeletal muscle tissue.

Selenium and its interrelation with mercury in wholeblood and hair in an East Greenlandic population

138 Blood samples and 12 hair samples from the district of Angmagssalik, East Greenland, have been analysed for selenium and mercury. It was found that selenium like mercury, was absorbed in accordance with the amount of marine food eaten. The mean blood concentration in the group eating most marine food was 173 and 186 micrograms Hg/1 for men and women, respectively, while in the group eating the lowest quantity of marine food, the mean values were 86 and 118 micrograms Hg/1. In blood, the selenium and mercury did not correlate in individuals, but only in groups according to eating habits. On a molar basis, selenium is present in blood in excess as compared to mercury, while the opposite is the case for hair. It is concluded that only part of the selenium interacts with mercury, and that blood, but not hair, reflects present dietary intake. The righ supply of selenium in relation to mercury exposure through the traditional arctic food is probably able to alleviate the hazards from dietary mercury exposure.

Erythrocyte antioxidant enzymes in multiple sclerosis and the effect of hyperbaric oxygen

The activities of catalase, glutathione peroxidase, and glutathione reductase, were not significantly different from normal whereas that of superoxide dismutase was decreased (P less than 0.05) in erythrocytes from patients with multiple sclerosis. Assay of the lipid peroxidation product, malondialdehyde, after incubation of erythrocytes with 10 mM H2O2 under carefully controlled conditions (peroxide stress test) demonstrated that MS erythrocytes are significantly (P less than 0.001) less susceptible to H2O2-induced lipid peroxidation in vitro. This finding suggests that the level of an endogenous antioxidant, possibly vitamin E, may be elevated in MS red cells. After treatment with hyperbaric O2, the activity of MS erythrocyte catalase is significantly (P less than 0.01) elevated by 2-6-fold.

Red blood cell glutathione peroxidase activity in multiple sclerosis

Glutathione peroxidase (GSH-Px) activity of red blood cells of 23 multiple sclerosis (MS) patients (10 men and 13 women, aged 22-64 years) was examined and compared to the enzyme activity of 26 healthy persons (15 men and 11 women, aged 19-50 years). It was found that the mean GSH-Px activity was significantly higher (P less than 0.001) in red blood cells of MS patients (39.1 +/- 8.1 IU/g Hb) as compared to the group of healthy persons (25.9 +/- 5.2 IU/g Hb). There was no difference according to sexes in both the MS patients and the control group. The results are discussed based on the hypothesis that organic peroxides play a role in the etiology of multiple sclerosis.

Superoxide dismutase, reduced glutathione and TBA-reactive products in erythrocytes of patients with multiple sclerosis

Superoxide dismutase, reduced glutathione and lipid peroxides levels were determined in the erythrocytes of multiple sclerosis patients. Superoxide dismutase activity and the malonyldialdehyde production rate were found to be significantly enhanced. The isoelectric focusing pattern of superoxide dismutase from multiple sclerosis and normal subjects erythrocytes was substantially overlapping. Our results indicate the occurrence of a higher susceptibility of multiple sclerosis erythrocytes to lipid peroxidation.

Glutathione peroxidase and reductase, glucose-6-phosphate dehydrogenase and catalase activities in multiple sclerosis

Our previous studies have demonstrated a decreased glutathione feroxidase (GSH-Px) activity of erythrocytes and leucocytes from multiple sclerosis (MS) patients. In the present communication these activities were compared with the activities of associated enzymes (glutathione reductase (GSSG-RD), glucose-6-phosphate dehydrogenase (G-6-PD) and catalase). All enzymic activities were compared between MS patients, other neurologic patients (ON patients) and normal control individuals. Compared to data of ON patients and normal controls, in MS the ratio of GSHPx/GSSGRD in lympho- and granulocytes was significantly decreased (2 alpha less than or equal to 0.05) by 35% and 51%, respectively. The significant correlation between GSSG-RD and the GSH-Px activity (2 alpha less than or equal to 0.05, r = 0.501) found in control lymphocytes was not present in MS lymphocytes. However, the lymphocyte GSH-Px activities of controls as well as of MS correlated with the corresponding serum selenium levels (2 alpha less than or equal to 0.05, r = 0.594 and 2 alpha less than or equal to 0.01, r = 0.967, respectively). The G-6-PD activity was insignificantly increased by 41% in MS lymphocytes compared to normal control. Catalase activity was unchanged in lymphocytes but decreased 50% in MS granulocytes compared to normal control. No significant differences were found between MS and the ON group. The catalase activity of MS erythrocytes was increased by 63% (2 alpha less than or equal to 0.05) in comparison with both the normal control and ON data.

Selenium and experimental allergic encephalomyelitis. The effects of different levels of dietary selenium on clinico-pathological findings

There are reports in which multiple sclerosis (MS) seems to be associated with abnormalities in selenium (Se) metabolism and erythrocyte glutathione-peroxidase (GSH-px) activity. Ordinary experimental allergic encephalomyelitis (EAE), which reflects some features of human MS, was induced in guinea pigs maintained with high, low and normal levels of Se in the diet. Evidence was obtained to indicate the following results: (i) a direct correlation between dietary Se levels and whole blood Se levels. (ii) Erythrocyte GSH-px activity was not found to be correlated with the blood Se content. (iii) The animals fed with low or normal levels of Se showed the same survival rates and developed EAE in a similar way and percentage. (iv) The animals fed with high non-toxic levels of Se showed a high incidence of death and some developed EAE with a subacute course, when compared with the other experimental groups. The results are discussed on the basis of findings in the literature.

Multiple sclerosis patients show an increased spontaneous activity of their peripheral blood monocytes as measured by chemiluminescence

I has been reported that myelin basic protein (BP) reacts extremely sensitively to peroxide, which is formed when monocytes/macrophages are stimulated to produce a "respiratory burst" (RB). We measured the RB activity by means of chemiluminescence in peripheral blood monocytes/macrophages (MO) of 17 MS patients, 5 patients with a viral infection of the CNS, and 14 control persons. The median of the spontaneous RB activity of MS patients compared with the median of our control group showed a highly significant increase (P = 0.0002). All MS patients examined possessed a clearly increased MO activity. The highest values, however, were found in MS patients in a bout (means = 315%, means = 296%). Since a viral infection is discussed as being involved in the pathogenesis of MS, we also examined patients with a viral infection of the CNS, but this group of patients did not show a significant increase (P = 0.34). Our data indicate that MO in MS patients generate and/or secrete an increased amount of unspecific mediators of inflammation. The possibility is discussed that this altered MO function might be caused by an altered reaction of MO in MS patients to a viral infection or superinfection.

Kinetics of selenite uptake by mononuclear cells from peripheral human blood

The present study deals with the kinetics and thermodynamics of the uptake of(75)Se-labeled SeO 3 (2-) from incubation media to lymphocytes cultivated from eight normal individuals (14-55 years of age, two females).The uptake of SeO 3 (2-) was evaluated on the assumption of pseudo-first-order kinetics with regard to a reacting cellular receptor pool. On the basis of the experimental observations, it was assumed that the suggested pool of receptor molecules-symbolically represented by "£H4"-reacts with SeO 3 (2-) in the hypothetical reaction:[Formula: see text] The mean value of the change in standard free energy at 25°C was calculated to be ΔG (o)=-141.6±1.3 kJ/mol, while the corresponding mean value of the free energy of activation at 25°C was calculated to be ΔG (2+)=-7.8±0.9 kJ/mol for the forward reaction.The calculated values of the corresponding individual changes in the respective standard enthalpies and entropies were mutually interdependent for all eight donors. ΔH (o)=-152+315ΔS (o)(kJ/mol) corresponding to the common value ΔG (o)≅-152 kJ/mol at 315°K. These mutual interdependencies are possibly the effect of variable conformational states (e.g., the macromolecular compactness) of the cellular receptor pools. This suggestion may furthermore be supported by the correlation traced between ΔH (o) vs the biological age in years of the donors: △H (°)≃76.7-1.0 (age)kJ/mol (r = -0.92)The calculated values of activation enthalpy ΔH (2+) kJ/mol and activation entropy ΔS (2+) (kJ/mol K) also mutually correlated linearly (r=0.998); the regression line was: △H (2+) = -8.9 + 305△S(2+) (kJ/mol) corresponding to the common value △H (2+) △ -8.9 (kJ/mol) at 305°KSimilarly the activation enthalpy ΔH (2+) vs the biological age in years correlated linearly: ΔH (2+)=67.4-0.73(age) (kJ/mol) (r=-0.76)The range of ΔH (2+) studied was from 13.8 to 53.9 kJ/mol with a linearly corresponding range in ΔS (2+) from 73 to 205 J/mol K.The thermodynamic data reveal the selenite uptake during the hypothetical standard reaction to be exergonic and endothermic. Critical pH dependencies of the selenite uptake were explained.