ADMA--a Possible Marker for Early Therapeutic Outcome in Acute Stroke.

BACKGROUND: Ischemic acute stroke is a leading cause for mortality and invalidity in recent years. Clinical trials show the role of ADMA as endogenous inhibitor of nitric oxide synthase and its connection to acute stroke. An early decrease of serum ADMA levels might help in recovery of the blood stream in patients with acute stroke and non-affective changes in the brain. METHODS: We compared 18 patients with acute stroke before and after thrombolysis and 21 patients (without history of cardiovascular disease, diabetes, kidney and liver injury, non-smokers) before and after thrombolysis. All results were compared to 30 healthy persons. Patients were evaluated by NIHSS, with ultrasound, CT and laboratory methods (traditional risk factors and CRP, D-dimmer, homocysteine, and ADMA). RESULTS: Classic vascular factors showed statistical significance in patients with acute stroke. Serum hsCRP levels and D-dimer in our study showed no connection to acute stroke. We found a statistically significant correlation in patients with stroke between ADMA and homocysteine levels (r = 0.469, p < 0.001). We found no significant difference between basic serum ADMA concentrations in groups with stroke who underwent different treatment (r = -0.449, p < 0.001). In patients with thrombolysis ADMA concentrations are reduced earlier, which also shows that earlier clinical recovery leads to no brain damaging effects. CONCLUSIONS: Through its pathophysiological changes, ADMA might be a predictor for acute stroke (along with already known risk factors) and can be a marker for the outcome of stroke, depending on the treatment.

Is There a Link Between Changes in Levels of Hepcidin and Stroke?

BACKGROUND: Iron is an essential element for the living body. It is well known that iron homeostasis disorders are important in two ways--its deficiency and its overload lead to several pathologies. METHODS: We measured 17 patients with iron deficiency anemia (IDA); 19 with anemia of chronic diseases (ACD); 15 with ischemic stroke (IS). The results were compared to a previously selected control group. For evaluation of iron metabolism status, we measured serum iron levels, ferritin, and soluble transferrin receptors. For inflammation, serum interleukin-6 and hsCRP were measured. Serum hepcidin quantification was performed using a previously validated immunosorbent method. Ferritin was measured by an ECLIA method; serum iron on AAS; hsCRP using a nephelometric analysis. RESULTS: We found statistically significant elevated serum hepcidin levels in patients with ACD and IS compared to the control group (p < 0.001). Patients with IDA had statistically significant lower hepcidin levels compared to the control group (p < 0.001). Serum ferritin levels in the IS group was higher compared to the control and other groups (p < 0.001). The lowest ferritin concentrations were established in the IDA group compared to the control (p < 0.001). We found a strong correlation between serum hepcidin and ferritin levels in the IS group (r = 0.583; p < 0.001). CONCLUSIONS: Quantification of serum hepcidin levels might be used as a link for prediction of acute ischemic stroke and future therapeutic influences.

Serum hepcidin levels in Bulgarian population.

BACKGROUND: Hepcidin is a 25-aminoacid cysteine-rich iron regulating peptide. Hepcidin quantification in human serum provides new insights for the pathogenesis of disorders of iron homeostasis. This study describes an ELISA immunoassay for hepcidin quantification in human serum and reference ranges for Bulgarian population. METHODS: We used a sandwich ELISA method from USCN Life Science inc. that consists of ready to use, pre-coated 96-well strip plate with 2 antihepcidin-25 monoclonal antibodies. A recombinant Hepcidin in 16 µg/L concentration is used as a standard. We correlated ELISA results of hepcidin-25 measurements in healthy population to ferritin, hemoglobin concentration in reticulocytes, transferrin, and iron levels. RESULTS: The sandwich ELISA was highly specific for hepcidin-25. We found that serum hepcidin levels for Bulgarian population are 3.052 µg/L - 37.750 µg/L, which is quite similar to that established by WCX-TOF MS from the Laboratory of Genetic, Endocrine and Metabolic Diseases; Dept. of Laboratory Medicine, Radbound University Medical Centre; Nijmegen, The Netherlands. Ferritin levels and hemoglobin concentration in reticulocytes correlated significantly to serum hepcidin levels (0.3 < r < 0.5, p < 0.010). Transferrin levels showed negative and no significant correlation to hepcidin in serum (r = -0.111). CONCLUSIONS: The use of two monoclonal antibodies in a sandwich ELISA format provides a reliable, reproducible, and not very expensive method for measuring serum concentrations of the bioactive form of hepcidin in Bulgarian laboratory practice.

Ascorbic acid--important for iron metabolism.

Ascorbic acid is actively involved in the control of iron metabolism. It has long been known to enhance absorption of iron from test meals. At first this effect was ascribed to luminal reduction and solubilsation of iron. Later, molecular cloning of mammalian duodenal brush-border reductase activity and studies in animals and man strongly supported ascorbate as the intracellular electron donor for duodenal ferri-reductase activity and provided molecular mechanism for an intracellular role of ascorbate in intestinal iron absorption. Factors that alter duodenal ascorbate levels (dietary intake of ascorbate, dehydroascorbate, or oxidants) may therefore alter the rate of absorption. Ascorbate could play dual role in human cells; it could react as pro-oxidant and as antioxidant. The balance of these contradictory effects depends on ascorbate concentration. Pro-oxidant reactions predominate at low concentrations; at higher concentrations vitamin C reacts as antioxidant. The increase of plasma ascorbate in human iron deficiency, especially in females in active age, could explain gender-related biological variation of plasma levels of vitamin C. The possible participation of ferric reductase activity Dcytb in transferrin cycle in liver and in neutrophil host defense implies new aspects of the role of vitamin C in the regulation of iron homeostasis.

Duodenal ascorbate and ferric reductase in human iron deficiency.

BACKGROUND: The first step in iron absorption requires the reduction of ferric iron to ferrous iron, a change that is catalyzed by duodenal ferric reductase. Iron deficiency is associated with high iron absorption, high ferric reductase activity, and high duodenal ascorbate concentrations in experimental animals, but it is not known whether a relation between reductase and ascorbate is evident in humans. OBJECTIVE: The objective of the study was to assess the relation between ferric reductase activity in human duodenal biopsy specimens and ascorbate concentrations in iron-replete and iron-deficient subjects. DESIGN: Patients and control subjects were overnight-fasted adults presenting sequentially for upper gastrointestinal endoscopic investigation. Ferric reductase activity in duodenal biopsy specimens was assayed by using nitroblue tetrazolium. Ascorbate was assayed in duodenal biopsy specimens and plasma. RESULTS: Iron-deficient patients had significantly higher reductase activity (n = 6-9; P < 0.05) and duodenal (n = 20; P < 0.001) and plasma (n = 6; P < 0.001) ascorbate concentrations than did control subjects. Incubation of biopsy specimens with dehydroascorbate (to boost cellular ascorbate) increased reductase activity in the tissues that initially had normal activity (n = 9; P < 0.01) but inhibited reductase activity in the tissues that already had high reductase activity (n = 13; P < 0.001). CONCLUSIONS: Iron deficiency in humans is associated with increased duodenal ascorbate concentrations. This finding suggests that increased reductase activity is partly due to an increase in this substrate for duodenal cytochrome b reductase 1.

Duodenal ascorbate levels are changed in mice with altered iron metabolism.

Ascorbate has long been thought to play an important role in intestinal iron absorption. The recent identification of a possible ascorbate-dependent duodenal ferric reductase suggests a role for intracellular ascorbate in the control of iron absorption. We set out to determine whether duodenal ascorbate concentrations are altered by treatments known to alter the rate of iron absorption and whether ascorbate levels affect duodenal reductase activity. Duodenal ascorbate was extracted and assayed by HPLC and/or a chemical assay. Ferric reductase was assayed in vitro with ferric nitrilotriacetate or nitroblue tetrazolium as substrates. Duodenal ascorbate concentrations were increased by iron deficiency, genetic hypotransferrinemia, and hypoxia. Parenteral iron overload increased iron stores but did not affect duodenal ascorbate concentrations. Hemolytic anemia induced in mice by phenylhydrazine injection also did not affect duodenal ascorbate concentrations. In vitro studies with incubated duodenum showed that decreased tissue ascorbate was associated with decreased mucosal ferric reductase activity, whereas incubation with dehydroascorbate prevented both the decrease in ascorbate concentration and reductase activity. Mouse duodenum ascorbate concentrations changed in response to treatments that altered iron absorption rates; in particular, ascorbate levels generally increased when iron absorption was increased by iron deficiency, hypoxia, or genetic hypotransferrinemia. We conclude that changes in ascorbate levels are associated with changes in ferric reductase activity. These findings are consistent with the proposal that duodenal ascorbate plays a role in intestinal iron absorption.