The role of aspirin and dipyridamole on vascular DNA synthesis and intimal hyperplasia following deendothelialization

Platelets are implicated both in acute thrombotic events and, through platelet-derived growth factor, in the development of intimal hyperplasia. We have investigated, in vivo, the influence of aspirin and dipyridamole on vascular smooth muscle cell proliferation and DNA synthesis following balloon catheter injury. Fifty-eight male, New Zealand white rabbits were divided equally into two groups; the test group was fed aspirin (14 mg/kg/day) and dipyridamole (9 mg/kg/day) from 2 days prior to surgery until sacrifice at 1, 2, 3, 4, 7, 14, or 28 days after injury. All animals were sacrificed 1 h after injection of [3H]thymidine and the smooth muscle cell DNA specific activity and total kinetic activity were determined. Intimal hyperplasia was measured by light microscopy and intimal nuclear proliferation was determined by counting nuclei per millimeter of internal elastic lamina. Nuclear proliferation was maximal at 14 days (25 +/- 1.2) but intimal hyperplasia was still increasing at 28 days. DNA specific activity after 24 hr (test: 4 +/- 2 dpm/micrograms DNA; control: 3.3 +/- 3 dpm/micrograms DNA) was similar to basal levels in uninjured rabbits. DNA synthesis peaked in both groups between the second and third day (test: 177 +/- 27 dpm/micrograms DNA; control: 185 +/- 39 dpm/micrograms DNA) and then declined slowly toward baseline values. There was no significant difference between treated and normal rabbits in either [3H]thymidine incorporation, nuclear proliferation, or development of intimal hyperplasia despite 90% inhibition of platelet aggregation and a significant reduction (78%) in [14C]serotonin release following collagen challenge (6 micrograms/ml).(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased vascular contraction and sensitivity to norepinephrine after endothelial denudation is inhibited by prazosin

The vasomotor function of rabbit aorta was examined after deendothelialization with a Fogarty balloon catheter and during the subsequent development of intimal hyperplasia. Helical strips of injured lower abdominal aortic tissue showed an increase in norepinephrine-induced contraction when compared with control strips from normal upper abdominal aorta. This increase was 235% +/- 40% of control immediately after injury and 341% +/- 51% at 28 days after injury. Standardized dose-response curves demonstrated that the injured tissue was increasingly sensitive over time to norepinephrine and that this was more marked at physiologic levels of norepinephrine. Contraction was blocked by prazosin hydrochloride but not by yohimbine or propranolol. Furthermore, a single intramuscular dose of prazosin hydrochloride 2 hours before injury significantly (p = 0.001) reduced the maximal contraction and sensitivity. These results imply an increase in vasomotor reactivity after deendothelialization mediated through the alpha 1-adrenergic receptor. These functional changes are related to the pertinent morphologic observations.     

Influence of haemodialysis on early markers of atherosclerosis

Introduction: End-stage renal disease (ESRD) patients treated by haemodialysis (HD) have impaired endothelium-dependent vasodilatation and increased intima-media thickness (IMT) of the carotid artery The aim of the study was to analyse the relationships between parameters of chronic HD treatment and non-invasive assessments of preclinical atherosclerosis (endothelial dysfunction and carotid IMT) in ESRD patients on HD. Methods: Fifty-two (19 females, 33 males) adult patients on chronic maintenance (4.65 ± 3.29 years) HD aged 59.88 ± 15.49 years were investigated. Ultrasonographic studies were performed with a 7.5 MHz high-resolution probe. The common carotid artery IMT was measured. Brachial artery diameter was analysed to the rest. In order to assess flow-mediated dilatation (FMD), hyperaemia was induced by a pneumatic cuff, and an analysis of the diameter was performed 1, 2, 3 and 4 min after cuff deflation. Results: Significant differences were found in the average carotid IMT value between subjects with delivered dialysis dose (Kt/V) ≥1.2 and <1.2 (0.89 ± 0.21 vs 1.04 ± 0.11, P = 0.0045). A correlation between Kt/V and IMT (r = 0.366, P = 0.004) was demonstrated. FMD values of the brachial artery did not correlate with Kt/V. A correlation between low molecular weight heparin per kg of body mass and maximal percent of FMD was demonstrated (r = −0.242, P = 0.049). The maximal percent of brachial FMD was correlated with absolute difference between pre- and postdialysis pulse pressure values (r = −0.265, P = 0.033). In a partial correlation with haemoglobin as control, a variable significant correlation between total erythropoietin dose and maximal carotid IMT (r = −0.262, P = 0.036) was found. In a multiple linear regression model, Kt/V was independently correlated with carotid IMT values (β = −0.227, P = 0.0335). Conclusion: This study has demonstrated the association between HD procedure and early atherosclerosis markers. HD treatment has to be considered as potential modifying factor in atherosclerosis development.     

Evaluation of genome damage and its relation to oxidative stress induced by glyphosate in human lymphocytes in vitro

In the present study we evaluated the genotoxic and oxidative potential of glyphosate on human lymphocytes at concentrations likely to be encountered in residential and occupational exposure. Testing was done with and without metabolic activation (S9). Ferric‐reducing ability of plasma (FRAP), thiobarbituric acid reactive substances (TBARS) and the hOGG1 modified comet assay were used to measure glyphosate's oxidative potential and its impact on DNA. Genotoxicity was evaluated by alkaline comet and analysis of micronuclei and other nuclear instabilities applying centromere probes. The alkaline comet assay showed significantly increased tail length (20.39 μm) and intensity (2.19%) for 580 μg/ml, and increased tail intensity (1.88%) at 92.8 μg/ml, compared to control values of 18.15 μm for tail length and 1.14% for tail intensity. With S9, tail length was significantly increased for all concentrations tested: 3.5, 92.8, and 580 μg/ml. Using the hOGG1 comet assay, a significant increase in tail intensity was observed at 2.91 μg/ml with S9 and 580 μg/ml without S9. Without S9, the frequency of micronuclei, nuclear buds and nucleoplasmic bridges slightly increased at concentrations 3.5 μg/ml and higher. The presence of S9 significantly elevated the frequency of nuclear instabilities only for 580 μg/ml. FRAP values slightly increased only at 580 μg/ml regardless of metabolic activation, while TBARS values increased significantly. Since for any of the assays applied, no clear dose‐dependent effect was observed, it indicates that glyphosate in concentrations relevant to human exposure do not pose significant health risk. Environ. Mol. Mutagen. 2009. © 2009 Wiley‐Liss, Inc.     

Overview of vasculitis and vasculopathy in rheumatoid arthritis—something to think about

The vasculature plays a crucial role in inflammation and atherosclerosis associated with the pathogenesis of rheumatoid arthritis. Vasculitis in rheumatoid arthritis is associated with longstanding disease, has an important impact on a patient’s quality of life and influences patient life expectancy. Seropositivity, specific human leukocyte antigen variations, antibodies to cyclic citrullinated peptides, and cigarette smoking are among the genetic and environmental predictors of rheumatoid vasculitis. Atherosclerosis is an early and common finding in rheumatoid arthritis and it correlates with disease duration, activity, and severity. Apart from conventional risk factors such as cigarette smoking, physical inactivity, obesity, arterial hypertension, dyslipidemia and diabetes mellitus, rheumatoid arthritis-related risk factors including disease duration, severity and activity, rheumatoid factor and antibodies to cyclic citrullinated peptides status, functional impairment, C-reactive protein, radiographic changes, presence of the shared epitope, and treatment modalities are all implicated in the development of accelerated atherosclerosis. Atherosclerosis is also considered an inflammatory disease; thus, it may share common pathogenic mechanisms with rheumatic diseases such as rheumatoid arthritis. Advances in treatment of rheumatoid arthritis with disease-modifying biologic and nonbiologic agents will probably continue to reduce the incidence of vasculitis. Since the goal of treatment for rheumatoid arthritis is to decrease inflammatory burden, successful treatment may theoretically reduce the risk of accelerated atherosclerosis.     

One percent of human circulating B lymphocytes are capable of producing the natural anti-Gal antibody

The natural anti-Gal antibody constitutes 1% of circulating IgG in humans and interacts specifically with the carbohydrate epitope Gal alpha 1-3Gal beta 1-4GlcNAc-R (the alpha-galactosyl epitope). In view of the unusually large amounts of this antibody in the serum, it was of interest to determine the proportion of circulating B lymphocytes capable of synthesizing anti-Gal. For this purpose, blood B lymphocytes were incubated with Epstein-Barr virus (EBV) and plated in microtiter wells. Proliferation of the EBV transformed B lymphocytes was readily visible after 3 weeks of incubation. The supernatants from wells containing proliferating B-lymphoid clones were assayed for anti-Gal by an agglutination assay with rabbit red blood cells and the specificity of the agglutinating antibodies was further confirmed by their interaction with synthetic oligosaccharides and by enzyme-linked immunosorbent assay with glycoproteins. Approximately 5% of the wells contained anti-Gal antibodies. Limiting dilution studies and IgH gene rearrangement patterns suggested that each well contained an average of five proliferating B-lymphoid clones. Thus, it is concluded that approximately 1% of circulating B lymphocytes are capable of producing anti-Gal. The proportion of anti-Gal--producing lymphoid clones exceeds by fourfold that of clones producing anti-blood group A or anti-blood group B antibodies. Individual anti-Gal clones display fine variations in their combining site, as indicated by their differential interaction with alpha-galactosyl epitopes on glycolipids and on N-linked carbohydrate chains of glycoproteins. The high frequency of precursor B lymphocytes capable of producing anti-Gal, found in every individual and the restricted specificity of this antibody to alpha-galactosyl epitopes, potentially makes anti-Gal--producing lymphocytes an effective system for studying human Ig genes involved in the natural immune response to structurally defined haptens.     

Antibodies contained in "M" component of some patients with multiple myeloma are directed to food antigens?

Multiple myeloma is malignant disease that is characterized in most patients, by the presence in the serum of monoclonal gamma globulins, which in agarose gel after electrophoresis appear as protein band of restricted mobility, “M” component.

The aim of this study was to determine are the antibodies contained in M-component directed to some antigen chronically present in the organism, to some of food antigens.

Seventeen patients with secretory plasmacytoma were included in the study: eight of them had IgG(kappa), three had IgG(lambda), and one had biclonal IgG(kappa) and IgA(kappa), while two had IgA(kappa), the other two IgA(lambda) and one IgM(lambda) as paraproteins. M-proteins were detected analyzing patients’ sera by agarose gel electrophoresis in 0.09 M barbital buffer. The each M-protein was confirmed by immunotyping (immunofixation) with corresponding antihuman antibodies directed to heavy or light chains of immunoglobulins. After the patients serum separation on agarose gel by electrophoresis, fresh 0.4% solution of crude gliadin (Sigma) in 1% SDS was put over the slides for immunoprecipitation.

Preliminary results showed the interaction of gliadin with patient's serum proteins present in the protein fraction of the same mobility as it was the mobility of the M-component, in 6 from 17 investigated sera.

These results are the first reporting that in sera of some patients with multiple myeloma antibodies from M-component could be directed to some of gliadin antigens.

As the serum antigliadin immunoreactivity is present in patients with gluten intolerance, celiac disease, it could be of importance to elucidate is the multiple myeloma more severe form of gluten intolerance than celiac disease.