Increased serum level of alpha-2 macroglobulin and its production by B-lymphocytes in chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL), the most common adult's leukemia in the western world, is caused in 95% of the cases by uncontrolled proliferation of monoclonal B-lymphocytes. The complement system in CLL is chronically activated at a low level via the classical pathway (CP). This chronic activation is induced by IgG-hexamers, which are formed after binding to alpha-2-macroglobulin (A2M). The study investigated for the first time the serum levels of A2M in CLL patients, their association with the disease severity, and A2M production by the malignant B-lymphocytes. Blood samples were collected from 65 CLL patients and 30 normal controls (NC) subjects, and used for quantifications of the A2M levels, the complement activation marker (sC5b-9), the complement components C2, C3 and C4, and clinical biochemistry and hematology parameters. The production of A2M was studied in B-lymphocytes isolated from blood samples as well as in CLL and non-CLL cell lines.The serum A2M levels were significantly higher in CLL patients vs NCs, showing values of 3.62 ± 0.22 and 1.97 ± 0.10 mg/ml, respectively. Within the CLL group, A2M levels correlated significantly with the disease stage, with sC5b-9, and with clinical indicators of the disease severity. Increased A2M production was showed in three out of four CLL B-lymphocytic lines that were studied, as compared to non-CLL lines, to a non-lymphocytic line, and to blood-derived primary B-lymphocytes. A2M production was further increased both in primary cells and in the CLL cell-line after incubation with CLL sera, compared to NC sera. This study shows for the first time that serum A2M levels in CLL are significantly increased, likely due to A2M production by the malignant B-lymphocytes, and are correlated with the disease severity and with chronic complement activation. The moderate change in A2M production after incubation with NC sera in-vitro supports the hypothesis that inhibition of excess A2M production can be achieved, and that this may potentially down-regulate the IgG-hexamerization and the resulting chronic CP activation. This may also help restore complement system activity, and eventually improve complement activity and immunotherapy outcomes in CLL.

Serum albumin levels and inflammation.

Albumin is the most abundant protein in the plasma and has a regulatory role in the distribution of body fluids, acid-base physiology, and binding of essential components in the bloodstream. C-reactive protein (CRP) is produced by hepatocytes and is commonly used to assess inflammation. It was previously noted that acute-phase concentrations of proteins, such as CRP, tend to rise in inflammatory conditions, while albumin concentrations tend to decline. This study assessed the correlation between albumin levels and various inflammatory indices (CRP, WBC, PLT) of patients hospitalized at the Galilee Medical Center over a period of 3 months. The study population consisted of 4434 patients, ages 18-107 years (mean: 52 years), of whom 60% were female. A negative correlation between albumin and CRP levels (r = -0.311) was identified, as well as between albumin and white blood cells levels (r = -0.157). Positive correlations were found between albumin and platelets levels (r = 0.084), as well as between albumin and hemoglobin levels (r = 0.513). When considering the three largest departments, the strongest negative correlation between albumin and CRP was identified in the Internal Medicine departments. A linear regression analysis discovered a fairly minor effect of CRP on albumin levels, which only became apparent when CRP levels were extremely high (500 mg/L). The mechanisms underlying this negative correlation still need to be explored.

Cell-free IgG-aggregates in plasma of patients with chronic lymphocytic leukemia cause chronic activation of the classical complement pathway.

Therapy regimens for Chronic lymphocytic leukemia (CLL) commonly include chemotherapy and immunotherapy, which act through complement-mediated-cytotoxicity (CDC) and other mechanisms. CDC depends on several factors, including the availability and activity of the complement classical pathway (CP). Recently, a significant decrease in CP activity was shown to be associated with an immunoglobulin-C5a complex (Ig-C5a) and other markers of chronic CP activation in 40% of the patients. The study focused on the involvement of IgG-hexamers, an established CP activator, in the mechanism of chronic CP activation in CLL. Sera from 51 naïve CLL patients and 20 normal controls were collected. CP and alternative pathway (AP) activities were followed by the complement activity marker sC5b-9. Serum high molecular weight (HMW) proteins were collected by gel-filtration chromatography and their complement activation capacity was assessed. The levels of IgM, another established CP activator, were measured. Data were associated with the presence of Ig-C5a. Baseline levels of activation markers negatively correlated with CP and the AP activities, supporting chronic complement activation. In patients with Ig-C5a, HMW proteins that are not IgM, activated the complement. HMW proteins were identified as IgG-aggregates by affinity binding assays and Western blot analysis. The data indicate chronic CP activation, mediated by cell-free IgG-hexamers as a cause of decreased CP activity in part of the CLL population. This mechanism may affect immunotherapy outcomes due to compromised CP activity and CDC.

The Role of Alpha 2 Macroglobulin in IgG-Aggregation and Chronic Activation of the Complement System in Patients With Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults in the western world. One of the treatments offered for CLL is immunotherapy. These treatments activate various cellular and biochemical mechanisms, using the complement system. Recently it was shown that the complement system in CLL patients is persistently activated at a low level through the classical pathway (CP). The mechanism of chronic CP activation involves the formation of IgG-hexamers (IgG-aggregates). According to recent studies, formation of ordered IgG-hexamers occurs on cell surfaces via specific interactions between Fc regions of the IgG monomers, which occur after antigen binding. The present study investigated the formation of IgG-hexamers in CLL patients and normal (non-malignant) controls (NC), their ability to activate complement, their incidence as cell-free and cell-bound forms and the identity of the antigen causing their formation. Sera from 30 patients and 12 NC were used for separation of IgG- aggregates. The obtained IgG- aggregates were measured and used for assessment of CP activation. For evaluation of the presence of IgG- aggregates on blood cells, whole blood samples were stained and assessed by flow cytometry. Serum levels of IgG- aggregates were higher in CLL and they activated the complement system to a higher extent than in NC. Alpha 2 macroglobulin (A2M) was identified as the antigen causing the hexamerization/aggregation of IgG, and was found to be part of the hexamer structure by mass spectrometry, Western blot and flow cytometry analysis. The presence of A2M-IgG-hexamers on B-cells suggests that it may be formed on B cells surface and then be detached to become cell-free. Alternatively, it may form in the plasma and then attach to the cell surface. The exact time course of A2M-IgG-hexamers formation in CLL should be further studied. The results in this study may be useful for improvement of current immunotherapy regimens.

A C5a-Immunoglobulin complex in chronic lymphocytic leukemia patients is associated with decreased complement activity.

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the Western world. The therapeutic approach to CLL includes chemotherapeutic regimens and immunotherapy. Complement-mediated cytotoxicity, which is one of the mechanisms activated by the therapeutic monoclonal antibodies, depends on the availability and activity of the complement (C) system. The aim was to study the structure of circulating C components and evaluate the importance of C5 structural integrity for C activity in CLL patients. Blood samples were collected from 40 naïve CLL patients and 15 normal controls (NC). The Western blot analysis showed abnormal C5 pattern in some CLL patients, while patterns of C3 and C4 were similar in all subjects. Levels of the C activation markers sC5b-9 and C5a were quantified before and after activation via the classical (CP) and alternative (AP) pathways. In patients with abnormal C5, basal levels of sC5b-9 and C5a were increased while activities of the CP and of the CP C5-convertase, the immediate C5-upstream complex, were decreased compared to NC and to patients with normal C5. The data indicate a link between CP activation and apparent C5 alterations in CLL. This provides a potential prognostic tool that may personalize therapy by identifying a sub-group of CLL patients who display an abnormal C5 pattern, high basal levels of sC5b-9 and C5a, and impaired CP activity, and are likely to be less responsive to immunotherapy due to compromised CP activity.

Free circulating active elastase contributes to chronic inflammation in patients on hemodialysis.

Atherosclerosis and cardiovascular complications are prevalent among patients undergoing chronic hemodialysis (HD). In this population, peripheral polymorphonuclear leukocytes (PMNLs) are primed, releasing proinflammatory mediators such as elastase. Elastase is normally inhibited by a specific inhibitor, avoiding undesirable degradation of cellular and extracellular components. This study tested the hypothesis that in states of noninfectious inflammation, elastase is released by PMNLs and acts in an uncontrolled manner to inflict vascular damage. Blood was collected from patients undergoing HD and healthy controls (HC). PMNL intracellular and surface expressions of elastase were determined by quantitative real-time PCR, Western blotting, and flow cytometry. The elastase activity was evaluated using a fluorescent substrate. The levels of serum α1-antitrypsin (α1-AT), the natural elastase inhibitor, were determined by Western blot. Free active elastase was elevated in HD sera, whereas the levels of α1-AT were decreased compared with HC. The levels of the intracellular elastase enzyme and its activity were lower in HD PMNLs despite similar expression levels of elastase mRNA. Elastase binding to PMNL cell surface was higher in HD compared with HC. The increased circulating levels of free active elastase released from primed HD PMNLs together with the higher cell surface-bound enzymes and the lower levels of α1-AT result in the higher elastase activity in HD sera. This exacerbated elastase activity could lead to the endothelial dysfunction, as hypothesized. In addition, it suggests that free circulating elastase can serve as a new biomarker and therapeutic target to reduce inflammation and vascular complications in patients on hemodialysis.

[LEVEL AND OXIDATION OF BETA 2-MICROGLOBULIN IN HEMODIALYSIS PATIENTS TREATED WITH INTRAVENOUS IRON DURING DIALYSIS WITH HIGH-FLUX COMPARED TO LOW-FLUX DIALYZERS].

INTRODUCTION: Serum levels of ß2-microglobulin (b2M) are significantly higher in patients with end stage renal failure undergoing hemodialysis (HD) and its accumulation accelerates Dialysis Related Amyloidosis (DRA). In HD patients low-flux dialysis, intravenous (IV) iron (administered for the treatment of anemia) affects ß2M removal during dialysis. IV iron also affects the oxidation of plasma proteins, including b2M. AIMS: To examine the effect of intravenous iron therapy on ß2M levels and oxidation in HD patients treated with high-flux compared with low-flux dialyzers. METHODS: Sixteen HD patients on chronic maintenance IV iron therapy were studied. Half of the patients were allocated to high-flux and half to low-flux dialysis. After five weeks, each patient was assigned to the second dialyzer. After two weeks of treatment with each dialyzer, blood samples were taken and serum levels of ß2M were measured. In addition, the hematocrit and iron status were measured. Part of the samples were used to evaluate oxidized ß2M. RESULTS: A significant increase in ß2M levels was found with low-flux dialysis, which further increased during dialysis with IV iron administration. High-flux dialysis therapy significantly lowered the ß2M levels, with a clear decrease during the dialysis session, that was unaffected by IV iron administration. A significant decrease in ß2M oxidation was found during highflux, but not low-flux dialysis. CONCLUSIONS: High-flux dialysis is more effective than lowflux in decreasing the levels and oxidation of ß2M. These observations may have significance in improving iron therapy, aimed to decrease or attenuate the appearance of DRA.

The relationship between oxidized serum albumin and blood pressure in hypoalbuminemic peritoneal dialysis patients.

BACKGROUND: Oxidative stress produces molecular modifications of serum albumin that disturb its biological functions and interfere with its detection by the bromocresol green assay (BCG). Oxidative stress, inflammation, and hypoalbuminemia are common peritoneal dialysis (PD). This study aimed to evaluate the relationship between serum albumin, oxidized serum albumin (OSA), oncotic pressure, and blood pressure in hypoalbuminemic PD patients. METHODS: Twenty-four PD patients with serum albumin levels <3.5 g/dl enrolled in the study. Data were compared between participants with the mean arterial pressure (MAP) <105 mmHg (n = 12) and MAP ≥ 105 mmHg (n = 12). RESULTS: Serum albumin levels were ≤3.0 g/dl and similar in both groups (p = 0.298). The calculated OSA and oncotic pressure were significantly higher in patients with MAP ≥ 105 mmHg than in those with MAP < 105 mmHg. MAP was positively and marginally correlated with serum albumin levels (measured by BCG) (r = 0.34, p = 0.05), and positively and significantly correlated with the calculated OSA and oncotic pressure (r = 0.44, p = 0.015, r = 0.58, p = 0.002; respectively). The oncotic pressure was positively correlated with the calculated OSA (r = 0.47, p = 0.011). CONCLUSION: OSA, undetectable by the commonly used BCG, may contribute to higher blood pressure in hypoalbuminemic PD patients.

In-vivo oxidized albumin- a pro-inflammatory agent in hypoalbuminemia.

Hypoalbuminemia of Hemodialysis (HD) patients is an independent cardiovascular risk factor, however, there is no mechanistic explanation between hypoalbuminemia and vascular injury. In the event of oxidative stress and inflammation to which HD patients are exposed, albumin is oxidized and undetected by common laboratory methods, rendering an apparent hypoalbuminemia. We wanted to show that these circulating modified oxidized albumin molecules cause direct vascular damage, mediating inflammation. Once these in-vivo albumin modifications were reduced in- vitro, the apparent hypoalbuminemia concomitantly with its inflammatory effects, were eliminated. Albumin modification profiles from 14 healthy controls (HC) and 14 HD patients were obtained by mass spectrometry (MS) analyses before and after reduction in- vitro, using redox agent 1,4 dithiothreitol (DTT). Their inflammatory effects were explored by exposing human umbilical endothelial cells (HUVEC) to all these forms of albumin. Albumin separated from hypoalbuminemic HD patients increased endothelial mRNA expression of cytokines and adhesion molecules, and augmented secretion of IL-6. This endothelial inflammatory state was almost fully reverted by exposing HUVEC to the in-vitro reduced HD albumin. MS profile of albumin modifications peaks was similar between HD and HC, but the intensities of the various peaks were significantly different. Abolishing the reversible oxidative modifications by DTT prevented endothelial injury and increased albumin levels. The irreversible modifications such as glycation and sulfonation show low intensities in HD albumin profiles and are nearly unobserved in HC. We showed, for the first time, a mechanistic link between hypoalbuminemia and the pro-inflammatory properties of in-vivo oxidized albumin, initiating vascular injury.

Unexpected Normal Colloid Osmotic Pressure in Clinical States with Low Serum Albumin.

BACKGROUND: In clinical states associated with systemic oxidative stress (OS) and inflammation such as chronic kidney disease (CKD), oxidative modifications of serum albumin impair its quantification, resulting in apparent hypoalbuminemia. As the maintenance of oncotic pressure/colloid osmotic pressure (COP) is a major function of albumin, this study examined the impact of albumin oxidation on COP, both in-vivo and in-vitro. METHODS: Patients with proteinuria and patients on chronic hemodialysis (HD) with systemic inflammation and OS were enrolled. Blood samples were collected from 134 subjects: 32 healthy controls (HC), proteinuric patients with high (n = 17) and low (n = 31) systemic inflammation and from 54 patients on chronic hemodialysis (HD) with the highest levels of OS and inflammation. RESULTS: In-vitro oxidized albumin showed significantly higher COP values than non-oxidized albumin at identical albumin levels. In vivo, in hypoalbuminemic HD patients with the highest OS and inflammation, COP values were also higher than expected for the low albumin levels. The contribution to COP by other prevalent plasma proteins, such as fibrinogen and immunoglobulins was negligible. We imply that the calculation of COP based on albumin levels should be revisited in face of OS and inflammation. Hence, in hypoalbuminemic proteinuric patients with systemic OS and inflammation the assumption of low COP should be verified by its measurements.

The impact of oxidized serum albumin on the oncotic pressure and hydration status of peritoneal dialysis patients.

OBJECTIVE: Hypoalbuminemia, fluid overload (FO), and oxidative stress (OS) may be related to cardiovascular morbidity and mortality in peritoneal dialysis (PD) patients. OS produces molecular modifications of serum albumin that interfere with its quantification by the commonly used bromocresol green assay. This study evaluated the impact of oxidized serum albumin (OSA) on oncotic pressure (OP) and hydration status. PATIENTS AND METHODS: Twenty-four stable hypoalbuminemic PD patients were enrolled in the study. After performing physical examination, assessment of the hydration status using a whole-body bioimpedance spectroscopy technique was performed, and blood samples were drawn for determination of OP, serum albumin levels, and OSA. RESULTS: Extracellular to total body water (E/TBW) ratio was higher in patients with FO ≥1.5 L with or without edema than in patients with FO <1.5 L (P≤0.043). E/TBW ratio was higher in patients with FO ≥1.5 L and edema compared to those with FO ≥1.5 L but without edema (P=0.004). OP was significantly higher in patients with FO ≥1.5 L and without edema compared to those with FO ≥1.5 L and with edema (P<0.001). Albumin-detection index (ADI) in patients with FO ≥1.5 L and without edema was similar to ADI in patients with FO <1.5 L (P=0.520). ADI was significantly lower in patients with FO ≥1.5 L and without edema compared to those with FO ≥1.5 L and edema (P=0.034). E/TBW ratio correlated positively with the ADI (r=0.60, P=0.001) and inversely with the OP (r=-0.54, P=0.002). CONCLUSION: Overhydration may be clinically undetectable in PD patients. Assessing the hydration status and measuring the total serum albumin levels, including the oxidized fraction, should be considered in evaluating hydration status in PD patients.

Albumin oxidation leads to neutrophil activation in vitro and inaccurate measurement of serum albumin in patients with diabetic nephropathy.

Previous studies suggest that oxidative modifications of serum albumin lead to underestimation of albumin concentrations using conventional assays. In addition, oxidation of serum albumin may cause neutrophil activation and further oxidation of albumin, which may result in a series of reciprocal cyclical processes. Because hypoalbuminemia, systemic inflammation, and oxidative stress are common in diabetic nephropathy patients, the aim of this study was to show that albumin modifications and neutrophil activation underlie these reciprocal systemic processes. Blood samples from a cohort of 19 patients with diabetic nephropathy and 15 healthy controls were used for albumin separation. An oxidation-dependent "albumin detection index," representing the detection efficacy of the universal bromocresol green assay, was determined for each subject. This index was correlated with serum albumin levels, various markers of oxidative stress or inflammation, and kidney function. Activation of separated neutrophils by glycoxidized albumin was assessed by the release of neutrophil gelatinase-associated lipocalin (NGAL) and myeloperoxidase (MPO). The albumin detection index of diabetic nephropathy patients was significantly lower compared to that of controls, correlating positively with serum levels of albumin and kidney function and negatively with albumin glycoxidation and inflammatory markers. Glycoxidized albumin had a direct role in neutrophil activation, resulting in NGAL and MPO release. The hypoalbuminemia observed in patients with diabetic nephropathy partially results from underestimation of modified/oxidized albumin using the bromocresol green assay. However, modified or oxidized albumin may lead to a cycle of accelerated oxidative stress and inflammation involving neutrophil activation. We suggest that the albumin detection index, a new marker of oxidative stress, may also serve as a biomarker of diabetic nephropathy severity and its progression.

Oxidative modifications impair albumin quantification.

BACKGROUND: Hypoalbuminemia is a measure of malnutrition, inflammation and a predictor of mortality in uremia. It is controversial whether albumin levels per se are associated with the clinical outcomes in uremic patients. The co-occurrence of hypoalbuminemia and oxidative stress in hemodialysis (HD) patients led us to hypothesize that oxidative modifications of albumin decrease its detection and influence albumin quantification. METHODS: Albumin levels are determined in clinical laboratories mainly by the bromocresol green (BCG) spectrophotometric assay. The detection of serum albumin was investigated in HD patients and in healthy controls using an "albumin-detection index", defined as the ratio between BCG read-out (albumin-specific) to total albumin. The detection efficacy of albumin was also investigated in vitro, after glycoxidation, HOCl-mediated-oxidation, and metal-catalyzed-oxidation. Oncotic pressure was measured to assess albumin function. RESULTS: The albumin-detection index of patients was significantly lower compared with controls, correlating negatively with oxidative stress markers (serum advanced oxidation protein products-AOPP and glycoxidized serum albumin) and positively with serum albumin levels. The albumin-detection index was also decreased after in vitro oxidation. CONCLUSIONS: The study shows, both in vivo and in vitro, decreased detection of oxidized albumin by a commonly-used clinical assay, thus providing the molecular link between oxidative stress and hypoalbuminemia. Oxidative stress as reflected by hypoalbuminemia, rather than actual albumin levels, may be related to cardiovascular morbidity outcomes in HD patient.

Decreased TFF2 expression in the gastric antrum in patients infected with CagA-positive Helicobacter pylori.

BACKGROUND: The trefoils factor family is a relatively new family of peptides. Their abundant expression in the epithelial cells of the gastrointestinal tract in the normal physiological state and in various ulcerative conditions suggests an important role in mucosal defense and repair. Infection with Helicobacter pylori interferes with normal mucosal activity. OBJECTIVES: To investigate whether H. pylori infection alters the expression of trefoils TFF1 and TFF2 in the gastric mucosa of patients with H. pylori-associated chronic active gastritis, positive or negative for the CagA strain. METHODS: During investigation for dyspepsia, gastric biopsies and blood samples were obtained from patients who underwent upper gastrointestinal endoscopy. Rapid urease testing, histology for determination of H. pylori-associated CAG and Western analysis for TFF1 and TFF2 expression with antisera were performed. CagA state was determined using a commercial kit. RESULTS: TFF2 expression was significantly reduced in both groups of patients with H. pylori-associated CAG compared to healthy patients without H. pylori infection, particularly in CagA-positive patients. TFF1 expression showed a tendency of reduction (not significant) in this group only. CONCLUSIONS: These results suggest that H. pylori-associated CAG has a deleterious effect on the expression of TFF2 in the gastric antrum. This reduced expression may contribute to the damage induced to the gastric mucosa by H. pylori.

[Expression of inflammatory mediators in meningitis].

BACKGROUND: Infectious diseases cause a systemic inflammatory reaction. In some cases of meningitis it is difficult to determine whether the disease is of bacterial, viral or non-infectious origin. In order to distinguish between bacterial and viral diseases the levels of various inflammatory markers are used to determine the severity of the disease and the clinical prognosis. OBJECTIVE: The purpose of this study was to determine whether the levels of different markers can be used to distinguish between bacterial or viral meningitis or non-infectious neurological disease. METHODS: Patients with bacterial meningitis (n= 8), viral meningitis (n= 17), non-infectious neurological diseases (n = 17) and healthy subjects (n = 15) were studied. The levels of soluble CD14 (sCD 14), interleukin-6 (IL-6), interleukin-1beta (IL-1beta) and soluble adhesion molecule-1 (sICAM-1) were determined in the blood of all participants and in spinal fluid only in patients who had clinical indication to perform lumbar puncture. RESULTS: All the patients showed significant differences in the levels of blood and CSF markers measured compared to healthy subjects. In the blood, although some differences were significant, there was overlapping between all values of the measured markers in patient blood samples excluding IL-6, for which levels were significantly different between the bacterial and viral meningitis. Interestingly, the levels of all markers showed significant differences among all groups of patients. CONCLUSIONS: Among the blood markers examined, IL-6 can be used to distinguish between bacterial and viral diseases. However, the levels of cytokines examined in CSF, can serve to distinguish between bacterial and viral meningitis and non-infectious diseases.

Salivary beta2-microglobulin analysis in chronic kidney disease and hemodialyzed patients.

BACKGROUND: Beta2-microglobulin (beta2m) is a major component in dialysis-related amyloidosis, a disabling disease affecting long-term dialysis patients. METHODS: Beta2m and other components were analyzed in saliva and serum from 53 individuals in 4 subgroups: healthy normal controls, diabetes mellitus (DM), chronic kidney disease (CKD) and hemodialysis (HD) patients. RESULTS: Median salivary and mean serum beta2m concentrations were 78% higher in both saliva (p = 0.048) and serum (p = 0.047) in DM patients; 118% (p = 0.016) and 907% (p = 0.007) higher, respectively, in CKD patients, and 328% (p = 0.0001) and 2,710% (p = 0.001) higher, respectively, in HD patients, compared with healthy controls. The correlation analysis between salivary and serum beta2m concentrations showed a low correlation rate in HD patients (r = -0.18), but was rather high in CKD patients (r = 0.50). CONCLUSIONS: Salivary analysis of beta2m is a reliable method for evaluating serum beta2m levels in CKD patients, and may help predict the potential for development of CKD-induced amyloidosis.

Intravenous iron-gluconate during haemodialysis modifies plasma beta2-microglobulin properties and levels.

BACKGROUND: Intravenous iron replacement therapy is routinely used for correction of anaemia in patients with end-stage renal failure. Free or labile iron, present both in parenteral iron formulations and in blood of haemodialysis (HD) patients, has the potential to induce severe oxidative processes. This study evaluated the acute in vivo effect of intravenous iron administration on the oxidation of plasma beta2-microglobulin (beta2m) and on its plasma levels after HD. METHODS: Iron-gluconate was administered intravenously to 14 patients receiving HD with low-flux cellulose-triacetate membranes during the first hour of the 4 h HD treatment. Each patient underwent three different dialysis treatments, during which an infusion of 62.5, 125 or 0 mg (control) of iron-gluconate was administered in random order. Plasma beta2m levels and iron parameters were monitored immediately before and after each HD treatment. The molecular isoforms of beta2m were studied by two-dimensional gel electrophoresis and western analysis. Levels of oxidized beta2m were evaluated by reaction with 2,4-dinitrophenylhydrazine and western analysis. RESULTS: Both doses of iron-gluconate caused remarkable changes in the molecular properties of beta2m, including shift in isoelectric point, molecular mass and degree of oxidation. Iron administration also limited the decline in plasma beta2m levels to <7.5%, compared with 27.9+/-2.7% during HD without iron. CONCLUSIONS: Intravenous iron-gluconate led to a characteristic increase in molecular weight and in negative charge of beta2m, both of which can be assumed to be consistent with reduced membrane sieving coefficients and membrane adsorption, and thus with reduced clearance of beta2m.

Relationship between vitellogenin and vitellin in a marine shrimp (Penaeus semisulcatus) and molecular characterization of vitellogenin complementary DNAs.

The source of yolk proteins in crustacean ovaries has been the subject of controversy for several decades, and both extraovarian and intraovarian synthesized proteins have been implicated. To offer a new insight into the relationship of vitellogenin (VTG) and vitellin (VT), a comparison of extraovarian VTG and ovarian VT of the marine shrimp Penaeus semisulcatus was performed at the protein and cDNA levels. Two cDNAs (7920 and 2068 nucleotides [nt]) were sequenced for VTG from the ovary and one cDNA (7920 nt) was sequenced from the hepatopancreas. VTG cDNA from hepatopancreas was similar to VTG cDNA from ovary. Although a VTG gene was also found in the males, approximately 7.8-kilobase transcripts were only detected in the ovary and hepatopancreas of females. The mRNA expression pattern was related to the stage of ovarian development and to the molt cycle, as determined by real-time polymerase chain reaction assay. VTG and VT apoproteins were composed of two and three major subunits, respectively, as shown by SDS-PAGE. N-terminal sequences of these subunits revealed the presence of a cleavage site at a consensus motif for a subtilisin-like endoprotease in VTG and VT and an additional cleavage site in VT revealed by an unidentified endoprotease. These results indicate that penaeid shrimps constitute a unique model for vitellogenesis, showing intraovarian gene expression and synthesis of yolk protein.

Carbonyl stress induced by intravenous iron during haemodialysis.

BACKGROUND: Anaemic haemodialysis (HD) patients are treated with erythropoietin and intravenous iron for effective erythropoiesis. Since iron is a potent inducer and aggravator of pre-existing oxidative processes in HD patients, this study was aimed to evaluate the acute in vivo effect of two recommended iron doses on protein oxidation during the HD session. METHODS: Iron gluconate was intravenously administered to HD patients in doses of 62.5 or 125 mg per session. A dialysis session without iron administration served as a control for each patient. Carbonylated fibrinogen and iron profile parameters were monitored before and after each session. Plasma carbonylated fibrinogen levels from healthy subjects and HD patients before dialysis were compared. Protein associated carbonyls were identified in plasma by derivatization with 2,4-dinitrophenylhydrazine followed by western analysis and were quantified by densitometry. RESULTS: HD patients on maintenance iron showed elevated carbonylated fibrinogen compared with healthy subjects. During a HD session, carbonyls on fibrinogen further increased when 125 mg iron gluconate was administered, but no changes were detected with 62.5 mg iron gluconate or in the absence of iron. The changes in carbonylated fibrinogen during dialysis showed a significant linear correlation with the calculated values of transferrin saturation and free transferrin. CONCLUSIONS: The significant acute increase in carbonylated fibrinogen with 125 mg iron gluconate suggests that this iron dose should be used with caution. As fibrinogen is highly susceptible to iron-induced oxidation in vivo, it may serve as a marker reflecting acute iron oxidative damage and as a tool in refinement of the existing clinical dose guidelines for intravenous iron therapy.