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The American Journal of Clinical... May 2008Zn(2+) stimulates secretory sphingomyelinase, which in turn produces ceramide, an important trigger of suicidal erythrocyte death or eryptosis. Eryptosis is...
BACKGROUND
Zn(2+) stimulates secretory sphingomyelinase, which in turn produces ceramide, an important trigger of suicidal erythrocyte death or eryptosis. Eryptosis is characterized by exposure of phosphatidylserine (PS) at the erythrocyte surface and by cell shrinkage. As macrophages are equipped with PS receptors, they bind, engulf, and degrade PS-exposing cells.
OBJECTIVE
We examined whether Zn(2+) stimulates ceramide formation and PS exposure of erythrocytes and thus may be able to trigger suicidal erythrocyte death.
DESIGN
In erythrocytes from healthy volunteers, PS exposure (Annexin V binding), cell volume (forward scatter), cytosolic Ca(2+) activity (Fluo3 fluorescence), and ceramide formation (anticeramide antibody) were determined by fluorescence-assisted cell sorting.
RESULTS
Exposure to Zn(2+) (> or = 25 micromol/L Zn(2+)) significantly increased annexin binding. The effect was paralleled by increase of cytosolic Ca(2+) activity (> or = 25 micromol/L Zn(2+)) and by ceramide formation (> or = 10 micromol/L Zn(2+)). Glucose depletion (24 h) similarly increased PS exposure, an effect significantly enhanced in the presence of Zn(2+) (> or = 10 micromol/L Zn(2+)).
CONCLUSION
Zn(2+) triggers suicidal erythrocyte death, an effect partially due to ceramide formation and an increase of cytosolic Ca(2+) activity.
Topics: Annexin A5; Apoptosis; Calcium; Cells, Cultured; Ceramides; Erythrocytes; Flow Cytometry; Glucose; Humans; Phosphatidylserines; Protein Binding; Zinc
PubMed: 18469280
DOI: 10.1093/ajcn/87.5.1530 -
Acta Obstetricia Et Gynecologica... Aug 2001The objective of this study was to test the hypothesis that maternal plasma, cord plasma and placental tissue lipid peroxidation products are increased and antioxidants...
BACKGROUND
The objective of this study was to test the hypothesis that maternal plasma, cord plasma and placental tissue lipid peroxidation products are increased and antioxidants are decreased in women with pre-eclampsia.
METHODS
Placenta, maternal and cord plasma were collected at delivery from 29 normal, 21 pre-eclamptic and six eclamptic women. Plasma was collected from 21 non-pregnant matched controls. The analyses were measured by HPLC and colorimetric assay.
RESULTS
Plasma maternal concentrations of uric acid, LPO, MDA, ascorbic acid, vitamin E and cholesterol were not significantly different in pre-eclampsia as compared with normal pregnancy. Plasma concentrations of ascorbic acid and vitamin E were not significantly different in normal pregnancy as compared with the non-pregnant controls. Cord plasma concentrations of MDA were significantly higher in eclampsia (1.16+/-0.26 micromol/l) as compared with normal pregnancy (0.79+/-0.05 micromol/l, p<0.02) and pre-eclampsia (0.83+/-0.05 micromol/l, p<0.05). Cord plasma concentrations of vitamin E were significantly higher in eclampsia (21.3+/-7.5 micromol/l) as compared with normal pregnancy (10.2+/-1.1 micromol/l, p<0.01) and pre-eclampsia (10.4+/-1.8 micromol/l, p<0.04). Placental concentrations of LPO, MDA and ascorbic acid were not significantly different in pre-eclampsia as compared with normal pregnancy. Plasma cord concentrations of LPO and placental concentrations of vitamin E were undetected for normal pregnant, pre-eclamptic and eclamptic women respectively. Uric acid concentrations were significantly increased in eclampsia as compared with the non-pregnant controls (p<0.0001), normal pregnant controls (p<0.0001) and pre-eclampsia (p<0.008).
CONCLUSIONS
The findings in this study do not show any evidence of deficiency in the maternal protective antioxidant systems or increased production of lipid peroxidation products, LPO and MDA in African women with pre-eclampsia as compared with normal pregnancy. However, there was evidence of increased cord plasma concentrations of MDA and vitamin E in eclampsia as compared with normal pregnancy and pre-eclampsia. The placenta may be effective in removing MDA. The antioxidant uric acid serves as a protective role whilst the antioxidant and oxidant capacity in the different study groups remained unchanged.
Topics: Adolescent; Adult; Ascorbic Acid; Black People; Case-Control Studies; Cholesterol; Eclampsia; Female; Fetal Blood; Humans; Lipid Peroxides; Malondialdehyde; Oxidative Stress; Placenta; Pre-Eclampsia; Pregnancy; Pregnancy Trimester, Third; Vitamin E
PubMed: 11531614
DOI: 10.1034/j.1600-0412.2001.080008719.x -
The Journal of Clinical Endocrinology... Apr 1999Sulfation is an important pathway of thyroid hormone metabolism that facilitates the degradation of the hormone by the type I iodothyronine deiodinase, but little is...
Sulfation is an important pathway of thyroid hormone metabolism that facilitates the degradation of the hormone by the type I iodothyronine deiodinase, but little is known about which human sulfotransferase isoenzymes are involved. We have investigated the sulfation of the prohormone T4, the active hormone T3, and the metabolites rT3 and 3,3'-diiodothyronine (3,3'-T2) by human liver and kidney cytosol as well as by recombinant human SULT1A1 and SULT1A3, previously known as phenol-preferring and monoamine-preferring phenol sulfotransferase, respectively. In all cases, the substrate preference was 3,3'-T2 >> rT3 > T3 > T4. The apparent Km values of 3,3'-T2 and T3 [at 50 micromol/L 3'-phosphoadenosine-5'-phosphosulfate (PAPS)] were 1.02 and 54.9 micromol/L for liver cytosol, 0.64 and 27.8 micromol/L for kidney cytosol, 0.14 and 29.1 micromol/L for SULT1A1, and 33 and 112 micromol/L for SULT1A3, respectively. The apparent Km of PAPS (at 0.1 micromol/L 3,3'-T2) was 6.0 micromol/L for liver cytosol, 9.0 micromol/L for kidney cytosol, 0.65 micromol/L for SULT1A1, and 2.7 micromol/L for SULT1A3. The sulfation of 3,3'-T2 was inhibited by the other iodothyronines in a concentration-dependent manner. The inhibition profiles of the 3,3'-T2 sulfotransferase activities of liver and kidney cytosol obtained by addition of 10 micromol/L of the various analogs were better correlated with the inhibition profile of SULT1A1 than with that of SULT1A3. These results indicate similar substrate specificities for iodothyronine sulfation by native human liver and kidney sulfotransferases and recombinant SULT1A1 and SULT1A3. Of the latter, SULT1A1 clearly shows the highest affinity for both iodothyronines and PAPS, but it remains to be established whether it is the prominent isoenzyme for sulfation of thyroid hormone in human liver and kidney.
Topics: Adult; Humans; Isoenzymes; Kinetics; Substrate Specificity; Sulfotransferases
PubMed: 10199779
DOI: 10.1210/jcem.84.4.5590 -
The American Journal of Clinical... Dec 2008Choline and betaine are linked to phospholipid and one-carbon metabolism. Blood concentrations or dietary intake of these quaternary amines have been related to the risk...
BACKGROUND
Choline and betaine are linked to phospholipid and one-carbon metabolism. Blood concentrations or dietary intake of these quaternary amines have been related to the risk of chronic diseases, including cardiovascular disease and the metabolic syndrome.
OBJECTIVE
We aimed to determine dietary predictors of plasma choline and betaine among middle-aged and elderly subjects recruited from an area without folic acid fortification.
DESIGN
This is a population-based study of 5812 men and women aged 47-49 and 71-74 y, within the Hordaland Health Study cohort. Plasma concentrations per increasing quartile of intake of foods, beverages, and nutrients were assessed by multiple linear regression analysis, and dietary patterns were assessed by factor analysis.
RESULTS
Plasma choline was predicted by egg consumption (0.16 micromol/L; P < 0.0001) and cholesterol intake (0.16 micromol/L; P < 0.0001), and betaine was predicted by consumption of high-fiber bread (0.65 micromol/L; P < 0.0001); high-fat dairy products (-0.70 micromol/L; P < 0.0001); complex carbohydrates, fiber, folate, and thiamine (0.66-1.44 micromol/L; P
CONCLUSION
In this population of middle-aged and elderly men and women, recruited from an area with relatively low folate intake, neither plasma choline nor betaine was positively associated with consumption of animal products, fruit, or vegetables, but each was positively associated with the intake of specific food items such as eggs (choline) and bread (betaine).
Topics: Aged; Betaine; Bread; Cardiovascular Diseases; Choline; Cohort Studies; Diet Surveys; Dietary Fats; Eggs; Factor Analysis, Statistical; Feeding Behavior; Female; Folic Acid; Food, Fortified; Humans; Linear Models; Male; Meat; Metabolic Syndrome; Middle Aged; Norway; Phospholipids
PubMed: 19064529
DOI: 10.3945/ajcn.2008.26531 -
Kidney International Dec 2000Myeloperoxidase-catalyzed oxidative pathways have recently been identified as an important cause of oxidant stress in uremia and hemodialysis (HD), and can lead to...
BACKGROUND
Myeloperoxidase-catalyzed oxidative pathways have recently been identified as an important cause of oxidant stress in uremia and hemodialysis (HD), and can lead to plasma protein oxidation. We have examined patterns of plasma protein oxidation in vitro in response to hydrogen peroxide (H2O2) and hypochlorous acid (HOCl). We measured thiol oxidation, amine oxidation, and carbonyl concentrations in patients on chronic maintenance HD compared with patients with chronic renal failure (CRF) and normal volunteers. We have also examined the effect of the dialysis procedure on plasma protein oxidation using biocompatible and bioincompatible membranes.
METHODS
Plasma proteins were assayed for the level of free thiol groups using spectrophotometry, protein-associated carbonyl groups by enzyme-linked immunosorbent assay, and oxidation of free amine groups using a fluorescent spectrophotometer.
RESULTS
In vitro experiments demonstrate HOCl oxidation of thiol groups and increased carbonyl formation. In vivo, there are significant differences in plasma-free thiol groups between normal volunteers (279 +/- 12 micromol/L), CRF patients (202 +/- 20 micromol/L, P = 0.005) and HD patients (178 +/- 18 micromol/L, P = 0.0001). There are also significant differences in plasma protein carbonyl groups between normal volunteers (0.76 +/- 0.51 micromol/L), CRF patients (13.73 +/- 4.45 micromol/L, P = 0.015), and HD patients (16.95 +/- 2.62 micromol/L, P = 0.0001). There are no significant differences in amine group oxidation. HD with both biocompatible and bioincompatible membranes restored plasma protein thiol groups to normal levels, while minimally affecting plasma protein carbonyl expression.
CONCLUSIONS
First, both CRF and HD patients have increased plasma protein oxidation manifested by oxidation of thiol groups and formation of carbonyl groups. Second, HD with biocompatible and bioincompatible membranes restored plasma protein thiol groups to normal levels. Third, these experiments suggest that there is a dialyzable low molecular weight toxin found in uremia that is responsible for plasma protein oxidation.
Topics: Amines; Biocompatible Materials; Blood Proteins; Humans; Hydrogen Peroxide; Hypochlorous Acid; In Vitro Techniques; Kidney Failure, Chronic; Membranes, Artificial; Oxidants; Oxidation-Reduction; Oxidative Stress; Phagocytes; Renal Dialysis; Sulfhydryl Compounds; Uremia
PubMed: 11115093
DOI: 10.1046/j.1523-1755.2000.00443.x -
The Journal of Infectious Diseases Nov 2009Hemolysis causes anemia in falciparum malaria, but its contribution to microvascular pathology in severe malaria (SM) is not well characterized. In other hemolytic...
BACKGROUND
Hemolysis causes anemia in falciparum malaria, but its contribution to microvascular pathology in severe malaria (SM) is not well characterized. In other hemolytic diseases, release of cell-free hemoglobin causes nitric oxide (NO) quenching, endothelial activation, and vascular complications. We examined the relationship of plasma hemoglobin and myoglobin to endothelial dysfunction and disease severity in malaria.
METHODS
Cell-free hemoglobin (a potent NO quencher), reactive hyperemia peripheral arterial tonometry (RH-PAT) (a measure of endothelial NO bioavailability), and measures of perfusion and endothelial activation were quantified in adults with moderately severe (n = 78) or severe (n = 49) malaria and control subjects (n = 16) from Papua, Indonesia.
RESULTS
Cell-free hemoglobin concentrations in patients with SM (median, 5.4 micromol/L; interquartile range [IQR], 3.2-7.4 micromol/L) were significantly higher than in those with moderately severe malaria (2.6 micromol/L; IQR, 1.3-4.5 micromol/L) or controls (1.2 micromol/L; IQR, 0.9-2.4 micromol/L; P < .001). Multivariable regression analysis revealed that cell-free hemoglobin remained inversely associated with RH-PAT, and in patients with SM, there was a significant longitudinal association between improvement in RH-PAT index and decreasing levels of cell-free hemoglobin (P = .047). Cell-free hemoglobin levels were also independently associated with lactate, endothelial activation, and proinflammatory cytokinemia.
CONCLUSIONS
Hemolysis in falciparum malaria results in NO quenching by cell-free hemoglobin, and may exacerbate endothelial dysfunction, adhesion receptor expression and impaired tissue perfusion. Treatments that increase NO bioavailability may have potential as adjunctive therapies in SM.
Topics: Adult; Anemia, Hemolytic; Endothelium, Vascular; Female; Hemoglobins; Humans; Malaria, Falciparum; Malaria, Vivax; Male; Middle Aged; Myoglobin; Nitric Oxide; Severity of Illness Index; Young Adult
PubMed: 19803726
DOI: 10.1086/644641 -
The American Journal of Clinical... May 2010Elevated homocysteine concentrations are associated with an increased risk of cardiovascular disease and a decline in cognitive function. Intakes of choline and betaine,...
BACKGROUND
Elevated homocysteine concentrations are associated with an increased risk of cardiovascular disease and a decline in cognitive function. Intakes of choline and betaine, as methyl donors, may affect homocysteine concentrations.
OBJECTIVE
The objective was to examine whether choline and betaine intakes, assessed from food-frequency questionnaires, are associated with total plasma homocysteine concentrations under both fasting and post-methionine-load conditions in both pre- and post-folic acid fortification periods in the United States.
DESIGN
We assessed the association between choline and betaine intakes and fasting and post-methionine-load homocysteine concentrations using the US Department of Agriculture revised food-composition tables and evaluated whether the associations varied by folic acid fortification periods in 1325 male and 1407 female participants in the sixth examination (1995-1998) of the Framingham Offspring Study.
RESULTS
A higher choline-plus-betaine intake was associated with lower concentrations of post-methionine-load homocysteine; the multivariate geometric means were 24.1 micromol/L (95% CI: 23.4, 24.9 micromol/L) in the top quintile of intake and 25.0 micromol/L (95% CI: 24.2, 25.7 micromol/L) in the bottom quintile (P for trend = 0.01). We found an inverse association between choline-plus-betaine intake and fasting homocysteine concentrations; the multivariate geometric mean fasting homocysteine concentrations were 9.6 micromol/L (95% CI: 9.3, 9.9 micromol/L) in the top quintile and 10.1 micromol/L (95% CI: 9.8, 10.4 micromol/L) in the bottom quintile (P for trend < 0.001). When we stratified by plasma folate and vitamin B-12 concentrations, the inverse association was limited to participants with low plasma folate or vitamin B-12 concentrations. In the postfortification period, the inverse association between choline-plus-betaine intake and either fasting or post-methionine-load homocysteine was no longer present.
CONCLUSIONS
Choline and betaine intakes were associated with both fasting and post-methionine-load total homocysteine concentrations, especially in participants with low folate and vitamin B-12 status. The inverse association between choline and betaine intakes and homocysteine concentrations was no longer present in the postfortification period.
Topics: Betaine; Cardiovascular Diseases; Choline; Cognition Disorders; Diet; Female; Folic Acid; Homocysteine; Humans; Male; Methionine; Vitamin B 12; Vitamin B 6
PubMed: 20219967
DOI: 10.3945/ajcn.2009.28456 -
Scandinavian Journal of Work,... Aug 2004The aim of this study was to evaluate different biomarkers of exposure to N-methyl-2-pyrrolidone (NMP), a widely used industrial chemical. For this purpose, differences...
OBJECTIVES
The aim of this study was to evaluate different biomarkers of exposure to N-methyl-2-pyrrolidone (NMP), a widely used industrial chemical. For this purpose, differences in toxicokinetics between men and women and between pure and water-mixed NMP were evaluated after dermal absorption.
METHODS
Six female and six male volunteers (groups 1 and 2) were topically exposed for 6 hours to 300 mg of NMP. An additional group of six male volunteers (group 3) was exposed to 300 mg of NMP in a 50% water solution. Blood and urine were sampled before, during, and up to 9 days after the exposure. Plasma and urine were analyzed using mass spectrometry.
RESULTS
For groups 1 and 2, 16% and 18% of the applied dose were recovered in the urine as the sum of NMP and its metabolites. For group 3, 4% was recovered. The maximal concentration of 5-hydroxy-N-methyl-2-pyrrolidone (5-HNMP) was 10, 8.1, and 2.1 micromol/l for groups 1, 2 and 3, respectively, in plasma and 420, 360 and 62 micromol/l in urine adjusted for density. For 2-hydroxy-N-methylsuccinimide (2-HMSI), the maximal concentration was 5.4, 4.5, and 1.3 micromol/l for groups 1, 2 and 3, in plasma, respectively, and 110, 82 and 19 micromol/l in urine adjusted for density. For 5-HNMP there was a difference in time to reach the maximal concentration depending on whether pure NMP or 50% NMP in water was used. No such difference was seen for 2-HMSI. The differences in kinetics between male and female volunteers were small.
CONCLUSIONS
Preferably 2-HMSI should be used as the biomarker of exposure to NMP.
Topics: Adult; Biomarkers; Female; Humans; Male; Middle Aged; Occupational Exposure; Pyrrolidinones; Sweden
PubMed: 15458014
DOI: 10.5271/sjweh.799 -
Journal of Dairy Science Jun 2010The aim of this study was to determine the nucleoside and nucleotide content in ovine and caprine milks at the colostral, transitional, and mature stages of lactation.... (Comparative Study)
Comparative Study
The aim of this study was to determine the nucleoside and nucleotide content in ovine and caprine milks at the colostral, transitional, and mature stages of lactation. Samples from 18 dairy sheep and 18 dairy goats were collected at 1, 2, 3, 4, 5, and 15 d postpartum. Separation and quantitation of the 5'-nucleotides (NT) and the nucleosides (NS) was performed by reverse phase HPLC. For each compound measured, considerable interindividual variation was recorded in both species of milk. The total NS content ranged from 57 to 132 micromol/L and from 54 to 119 micromol/L in ovine and caprine milk, respectively. The major NS identified in both species of milk was uridine, representing more than 60% of the total NS pool. The mean levels of inosine and guanosine were comparable between ewe and goat milk. Instead, the mean level of cytidine across the sampling period was much higher in ewe milk (11.9 micromol/L compared with 4.5 micromol/L in goat milk) and exhibited a peak value on the fourth day of lactation. The adenosine content was at least 3-fold higher in caprine milk compared with its ovine counterpart. The total NS and orotic acid contents did not differ significantly between the 2 species. However, in the case of total NT content, interspecies differences were significant, with NT levels ranging from 294 to 441 micromol/L in ovine milk and from 166 to 366 micromol/L in caprine milk. The NT content in colostrum (1-3 d) of both species was higher than in mature milk (15 d), and uridine monophosphate was the dominant NT in all samples.
Topics: Adenosine; Adenosine Monophosphate; Animals; Cattle; Chromatography, High Pressure Liquid; Colostrum; Cytidine; Cytidine Monophosphate; Female; Goats; Guanosine; Inosine; Lactation; Milk; Nucleosides; Nucleotides; Uridine; Uridine Monophosphate
PubMed: 20494137
DOI: 10.3168/jds.2009-2836