Studies on the interactions between C-reactive protein and complement proteins

Several studies have investigated the interactions between C-reactive protein (CRP) and various complement proteins but none of them took into consideration the different structural forms of CRP. The aim of our study was to investigate whether the different antigenic forms of CRP are able to bind C1q, to trigger activation of the C1 complex and to study the ability of the various CRP forms to bind complement factor H (FH) and C4b-binding protein (C4BP). Interactions between various CRP forms and complement proteins were analysed in enzyme-linked immunosorbent assay and surface plasmon resonance tests and activation of the C1 complex was followed in a reconstituted system using purified C1q, C1r and C1s in the presence of C1-INH. Native, ligand-unbound CRP activated the classical pathway weakly. After binding to phosphocholine, native CRP bound C1q and significantly activated C1. Native CRP complexed to phosphocholine did not bind the complement regulatory proteins FH and C4BP. After disruption of the pentameric structure of CRP, as achieved by urea-treatment or by site-directed mutagenesis, C1q binding and C1 activation further increased and the ability of CRP to bind complement regulatory proteins was revealed. C1q binds to CRP through its globular head domain. The binding sites on CRP for FH and C4BP seemed to be different from that of C1q. In conclusion, in parallel with the increase in the C1-activating ability of different CRP structural variants, the affinity for complement regulatory proteins also increased, providing the biological basis for limitation of excess complement activation.     

T‐bet is a new synergistic meeting point for the BCR and TLR9 signaling cascades

The importance of the BCR and TLR9 in autoimmunity and in the production of auto‐antibodies is well established but the underlying molecular mechanism still needs to be determined. Here, we aim to characterize the BCR‐TLR9 cross‐talk by its effect on T‐bet, as T‐bet is activated and regulated by both receptors and has an important role in class‐switching to pathological IgG2a in mice. Using primary mouse B cells, we demonstrate that T‐bet expression is synergistically elevated by the cross‐talk between the BCR and TLR9. To test the effect of this synergy on IgG2a‐switching, the levels of switched B cells were checked by functional tests. We found that BCR costimulation had no additional effect on TLR9‐induced IgG2a expression, however the expression of Rad51 was synergistically increased. To check the biological significance of the synergy, we compared T‐bet expression in B cells from healthy and collagen‐induced arthritis mice but no differences were found. Taken together, we demonstrate here that signaling cascades driven by the BCR and TLR9 have a newly identified meeting point at T‐bet. The two cascades act synergistically on T‐bet; however additional signals may be needed to induce prolonged functional responses such as class‐switch recombination.     

Changes in cognitive function in patients with diabetes mellitus

Patients with diabetes are approximately 1.5 times more likely to experience cognitive decline than individuals without diabetes mellitus. Most of the data suggest that patients with diabetes have reduced performance in numerous domains of cognitive function. In patients with type 1 diabetes, specific and global deficits involving speed of psychomotor efficiency, information processing, mental flexibility, attention, and visual perception seem to be present, while in patients with type 2 diabetes an increase in memory deficits, a reduction in psychomotor speed, and reduced frontal lobe (executive) functions have been found. The complex pathophysiology of changes in the central nervous system in diabetes has not yet been fully elucidated. It is important to consider the patient's age at the onset of diabetes, the glycemic control status, and the presence of diabetic complications. Neurological consequences of diabetes appear parallel to those observed in the aging brain. Neuroimaging studies highlight several structural cerebral changes, cortical and subcortical atrophy, beside increased leukoaraiosis that occurs in association with diabetes. There is supporting evidence from many hypotheses to explain the pathophysiology of cognitive decline associated with diabetes. The main hypotheses pointing to the potential, implied mechanisms involve hyperglycemia, hypoglycemia, microvascular disease, insulin resistance, hyperinsulinism, hyperphosphorylation of tau protein, and amyloid-β deposition.     

Effect of some non-steroidal antiinflammatory drugs and isomeric dihydroxy benzoic acids on the AAPH initiated degradation of crocin

The authors examined the possible peroxyl radical scavanger effect of some non-steroidal antiinflammatory drugs and isomeric dihidroxy benzoic acids by means of the test based on 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-initiated degradation of crocin. The method is based on spectrophotometric determination of crocin, of which rate of AAPH-initiated degradation can be decreased in the presence of antioxidants with peroxyl radical scavanger activity. The authors studied the crocin degradation-inhibitory effect of phenacetin, paracetamol (acetaminophen), indomethacin, ibuprofen, diclofenac sodium, salicylic acid, salicylamide as well as the 2,3-, 2,4-, 2,5- and 3,4-dihydroxy substituted benzoic acids in 200 microM concentration. In the 60 minute studies the 2,3-, 2,5- and 3,4-dihydroxy benzoic acids proved to show the most effective degradation inhibitory effect. The results draw attention to the different antioxidant activity of salicylic acid and its hydroxylated metabolites (2,3- and 2,5-dihydroxy benzoic acids) formed under physiological conditions.     

Breakfast habits and factors influencing food choices at breakfast in relation to socio-demographic and family factors among European adolescents. The HELENA Study

Breakfast consumption has been shown to be an important indicator of a healthy lifestyle. Little is known however about factors influencing breakfast consumption and food choices at breakfast in adolescents. The aim of the present study was therefore to describe breakfast habits, and factors influencing food choices at breakfast within the framework of the EU-funded HELENA Study, in 3528 adolescents from ten European cities. Additionally, socio-demographic differences in breakfast habits and in influencing factors were investigated. Half of the adolescents (and fewer girls than boys) indicated being regular breakfast consumers. Girls with mothers with a high level of education, boys from 'traditional' families and boys who perceived low family affluence were positively associated with breakfast consumption. Boys whose parents gave encouragement and girls whose peers ate healthily were more likely to be regular breakfast consumers. 'Hunger', 'taste', 'health concerns' and 'parents or guardian' were the most important influences on the adolescents' food choices at breakfast. Adolescents from southern Europe and girls reported to be more influenced by personal and socio-environmental factors. Socio-demographic differences, in particular regional and gender differences, need to be considered in discussions surrounding the development of nutritional intervention programs intended for adolescents.     

The risk of early and late lung sequelae after conformal radiotherapy in breast cancer patients

PURPOSE: To study the risks of early and late radiogenic lung damage in breast cancer patients after conformal radiotherapy. METHODS AND MATERIALS: Radiogenic lung sequelae were assessed prospectively in 119 patients by means of clinical signs, radiologic abnormalities, and the mean density change (MDC) of the irradiated lung on CT. RESULTS: Significant positive associations were detected between the development of lung abnormalities 3 months or 1 year after the radiotherapy and the age of the patient, the ipsilateral mean lung dose (MLD), the radiation dose to 25% of the ipsilateral lung (D(25%)) and the volume of the ipsilateral lung receiving 20 Gy (V(20 Gy)). The irradiation of the axillary and supraclavicular lymph nodes favored the development of pneumonitis but not that of fibrosis. No relation was found between the preradiotherapy plasma TGF-beta level and the presence of radiogenic lung damage. At both time points, MDC was strongly related to age. Significant positive associations were demonstrated between the risks of pneumonitis or fibrosis and the age of the patient, MLD, D(25%), and V(20 Gy). A synergistic effect of MLD, D(25%), and V(20 Gy) with age in patients older than 59 years is suggested. CONCLUSION: Our analyses indicate that the risks of early and late radiogenic lung sequelae are strongly related to the age of the patient, the volume of the irradiated lung, and the dose to it.     

Effects of d- and l-limonene on the pregnant rat myometrium in vitro

Aim

To study the effects of d- and l-limonene on pregnant rat myometrial contractility in vitro, and investigate how these effects are modified by other agents. D- and l-limonene (10⁻¹³-10⁻⁸ M) caused myometrial contraction in a dose-dependent manner.

Methods

Contractions of uterine rings from 22-day-pregnant rats were measured in an organ bath in the presence of d- or l-limonene (10⁻¹³-10⁻⁸ M) and nifedipine (10⁻⁸ M), tetraethyl-ammonium (10⁻³ M), theophylline (10⁻⁵ M), or paxilline (10⁻⁵ M). Uterine cyclic adenosine monophosphate (cAMP) level was detected by enzyme immunoassay. Oxidative damage was induced by methylglyoxal (3 × 10⁻² M) and the alteration was measured via noradrenaline (1 × 10⁻⁹ to 3 × 10⁻⁵ M) -induced contractions.

Results

Pre-treatment with nifedipine (10⁻⁸ M), tetraethylammonium (10⁻³ M), and theophylline (10⁻⁵ M) attenuated the contracting effect of d- and l-limonene, while in the presence of paxilline (10⁻⁵ M) d- and l-limonene were ineffective. The two enantiomers decreased the myometrial cAMP level, but after paxilline pretreatment the cAMP level was not altered compared with the control value. Additionally, l-limonene (10⁻⁶ M) diminished consequences of oxidative damage caused by methylglyoxal (3 × 10⁻² M) on contractility, whereas d-limonene was ineffective.

Conclusion

Our findings suggest that l-limonene has an antioxidant effect and that both d-and l-limonene cause myometrial contraction through activation of the A_2A receptor and opening of the voltage-gated Ca²⁺ channel. It is possible that limonene-containing products increase the pregnant uterus contractility and their use should be avoided during pregnancy.Over the past few decades there has been a significant increase in the usage of self-prescribed complementary and alternative medication during pregnancy, such as herbal remedies, relaxation therapies, and aromatherapy (1-3). These products are mistakenly perceived to be safe and are mostly used in treating anxiety, insomnia, fatigue, back pain, constipation, and heartburn (1-5). For example, almond oil is widely believed to be a good nutrient for the developing fetus, however it has been proven to induce preterm birth (3). Since there is a lack of evidence on the safety of herbal medications and essential oils use during pregnancy, more information on this issue should be obtained.Limonene is a chiral molecule classified as a monoterpene and occurring as two optical enantiomers: d-limonene or [R(+)-enantiomer] and l-limonene or [S(-)-enantiomer] (6). It is mostly present in plants in its d-enantiomeric form or, to a lesser extent, as a racemic mixture (7). Limonene is a major component of several plant essential oils, including orange, lemon, mandarine, lime, and grapefruit. Because of its pleasant lemon-like sweet fragrance it is widely used as an additive to perfumes, soaps, foods, chewing gums, and beverages (8). D-limonene is also used therapeutically to dissolve cholesterol-containing bilestones (9) and relieve heartburn (10). It is rapidly and almost completely absorbed from the gastrointestinal tract (11). D-limonene has low toxicity and does not have any mutagenic, carcinogenic, or nephrotoxic risk to humans (12). Furthermore, it has a chemotherapeutic (13), anti-inflammatory (14), anxiolytic (15), antinociceptive (16), and potent antioxidant effects (17). It modifies the myometrial relaxing effect of terbutaline and decreases its cervical resistance-enhancing effect, however little is known about its mechanism of action (18). Some monoterpenoids have known mechanisms of action: eg, camphor and borneol are non-competitive inhibitors of neural acetylcholine receptors (19) and thymol inhibits Ca²⁺ and K⁺ channels in human ventricular cardiomyocytes (20). Monoterpenes induce vascular smooth muscle relaxation in rat mesenteric arteries through activation of large conductance Ca²⁺-activated potassium (BK_Ca) channels and inhibition of the L-type Ca²⁺ channels (21), and relaxation in isolated rabbit ileum through NO pathway and inhibition of L-type Ca²⁺ channels (22). Eucalyptol induces relaxation in rat and guinea-pig airway smooth muscle through non-specific mechanisms (23).Since no experiments have been carried out to investigate the effect of limonene on myometrial smooth muscle, our primary aim was to study the effects of limonene on pregnant Sprague-Dawley rat myometrium on the last day of pregnancy in vitro. Since intracellular Ca²⁺ plays an important role in the mechanism of action of monoterpenoids (21-23), our second aim was to investigate how the myometrial effect of limonene can be modified in the presence of the L-type Ca²⁺ channel blocker nifedipine, selective BK_Ca channel blocker paxilline, non-selective potassium channel blocker tetraethyl-ammonium (TEA), and non-selective adenosine receptor antagonist theophylline.     

The multiple function of Grb2 associated binder (Gab) adaptor/scaffolding protein in immune cell signaling

The Grb2 associated binder (Gab) adaptor/scaffolding protein family comprises conserved proteins: mammalian Gab1, Gab2 and Gab3, Drosophila Dos and Caenorhabditis elegans Soc1. Gab adaptors are involved in multiple signaling pathways mediated by receptor- and non-receptor protein tyrosine kinases (PTKs), and become phosphorylated upon stimulation by growth factors-, cytokines-, Ig Fc- and antigen receptors. Through its phosphorylated tyrosine containing motifs, proline-rich sequences and pleckstrin homologue (PH) domain Gab adaptors may generate an interacting platform for proteins with SH2 and SH3 domains and may transfer these molecules to the plasma membrane, thereby contributing to their activation. This review will concentrate on the function of mammalian Gab proteins in the signal transduction triggered by immune receptors.