Cholic acid changes defense response to oxidative stress in soybean induced by <Emphasis Type="Italic">Aspergillus niger</Emphasis>

The oxidative stress and antioxidant systems in soybean leaves and roots infected with plant pathogen Aspergillus niger were studied following treatment with different concentrations of cholic acid. Several oxidative stress parameters were analyzed: production of superoxide (O₂ ^·−) and hydroxyl radicals (^·OH), lipid peroxidation (LP), and superoxide dismutase (SOD; EC 1.15.1.1) activity, as well as the content of reduced glutathione (GSH). Results showed that inoculation with A. niger led to the increase of O₂ ^·− production and GSH quantities in leaves and ^·OH in roots. The highest activity of SOD occured in infected plants treated with cholic acid in concentrations of 40 and 60 mg L⁻¹ which ultimately led to a decrease in O₂ ^·− production. Inoculation with Aspergillus in combination with elevated cholic acid concentrations also increased ^·OH production which is correlated with increased LP. These results may support the idea of using cholic acid as an elicitor to trigger hypersensitive response in plant cells. Use of cholic acid may also actively contribute to soybean plants defense response against pathogen attack.     

Identification of genes coding for B cell antigens of Mycoplasma mycoides subsp. mycoides Small Colony (MmmSC) by using phage display

Background  

Contagious bovine pleuropneumonia (CBPP) is a mycoplasmal disease caused by Mycoplasma mycoides subsp. mycoides SC (MmmSC). Since the disease is a serious problem that can affect cattle production in parts of Africa, there is a need for an effective and economical vaccine. Identifying which of the causative agent's proteins trigger potentially protective immune responses is an important step towards developing a subunit vaccine. Accordingly, the purpose of this study was to determine whether phage display combined with bioinformatics could be used to narrow the search for genes that code for potentially immunogenic proteins of MmmSC. Since the production of IgG2 and IgA are associated with a Th₁ cellular immune response which is implicated in protection against CBPP, antigens which elicit these immunoglobulin subclasses may be useful in developing a subunit vaccine.     

Clinical course of uremic neuropathy in long-term hemodialysis

One hundred and thirty-one patients on long-term hemodialysis were examined for the presence of clinical symptoms and signs, and for the effects of dialytic age, age and sex on uremic neuropathy. According to dialysis age, the patients were divided into three subgroups: low dialysis age, < 5 years of dialysis (n = 58); intermediate dialysis age, 5-10 years of hemodialysis (n = 39); and high dialysis age, > 10 years of dialysis (n = 34). Two patient subgroups were differentiated according to mean age of 53.2 years: younger (n = 57) and older (n = 74). Clinical grading of uremic neuropathy was based on Nielsen's criteria. The most common symptoms were restless legs syndrome (47%) and cramps (51%). Sensory symptoms were less common in patients on long-term hemodialysis, most common of them being paresthesia (29%) and burning feet syndrome (28%). Abnormal Achilles reflex (53%) and impaired vibration sense (59%) were the most common clinical signs. Clinically manifested uremic neuropathy was present in more than 80% of all study patients, i.e. mild in 41%, and moderate to severe forms of uremic neuropathy according to Nielsen's criteria in 39%. There was no evident effect of dialytic age and sex on the clinical course of uremic neuropathy, however, there was a clear impact of age. It is concluded that long-term hemodialysis does not influence the clinical course of uremic neuropathy unlike evident deterioration of electroneurophysiologic findings.     

Micronuclei as a marker for medical screening of subjects continuously occupationally exposed to low doses of ionizing radiation

Context: Genotoxicity assays are widely employed in human biomonitoring studies to assess genetic damage inflicted by genotoxic agents.

Objective: Evaluation of micronuclei (MN) as a screening marker of occupational ionizing radiation (IR) exposure.

Materials and methods: Using micronucleus test, peripheral blood lymphocytes (PBL) of 402 control and exposed subjects were screened for genetic damage.

Results: The mean frequencies of micronucleus test parameters were significantly higher in exposed persons. Increase of micronucleus yield with duration of exposure (DOE) by 0.303MN/year was revealed.

Discussion and conclusion: The obtained data encourage us to consider MN as valuable markers for preventive medical screening of occupationally exposed groups.     

Strategies for folding of affinity tagged proteins using GroEL and osmolytes

Obtaining a proper fold of affinity tagged chimera proteins can be difficult. Frequently, the protein of interest aggregates after the chimeric affinity tag is cleaved off, even when the entire chimeric construct is initially soluble. If the attached protein is incorrectly folded, chaperone proteins such as GroEL bind to the misfolded construct and complicate both folding and affinity purification. Since chaperonin/osmolyte mixtures facilitate correct folding from the chaperonin, we explored the possibility that we could use this intrinsic binding reaction to advantage to refold two difficult-to-fold chimeric constructs. In one instance, we were able to recover activity from a properly folded construct after the construct was released from the chaperonin in the presence of osmolytes. As an added advantage, we have also found that this method involving chaperonins can enable researchers to decide (1) if further stabilization of the folded product is required and (2) if the protein construct in question will ever be competent to fold with osmolytes.     

Effects of chronic dietary exposure to a low-dose of Malathion, Aroclor-1254 and 3-methylcholanthrene on three biomarkers in male mice

The aim of this research was to examine the applicability of some chronic toxicological tests in the determination of exposure to xenobiotics present in concentrations below No Observed Adverse Effect Level (NOAEL) and below the detection limit of analytical instruments. In the present experiment tested chemicals (Malathion, Aroclor-1254 and 3-methylcholanthrene (3-MC)) were mixed with wheat grains and given to male mice as feed over a period of 12 months. 7-ethoxyresorufin-O-deethylase (EROD) activity with the 3-MC and Aroclor-1254 treatments reached the peak at 9th month of exposure (26.7 and 42.4 pmol?1 mg(prot)-?1, respectively), while malathion did not have significant influence. Glutathione (GSH) level depletion was highest after three months of exposure. Unexpectedly, acetylcholinesterase (AChE) activity increased after treatment with malathion, an organophosphorous insecticide. In conclusion, low-level concentrations chronically administered exert certain effects on the levels of selected enzymes, e.g. biomarkers.     

Structures of apo- and holo-tyrosine phenol-lyase reveal a catalytically critical closed conformation and suggest a mechanism for activation by K+ ions

Tyrosine phenol-lyase, a tetrameric pyridoxal 5'-phosphate dependent enzyme, catalyzes the reversible hydrolytic cleavage of L-tyrosine to phenol and ammonium pyruvate. Here we describe the crystal structure of the Citrobacter freundii holoenzyme at 1.9 A resolution. The structure reveals a network of protein interactions with the cofactor, pyridoxal 5'-phosphate, and details of coordination of the catalytically important K+ ion. We also present the structure of the apoenzyme at 1.85 A resolution. Both structures were determined using crystals grown at pH 8.0, which is close to the pH of the maximal enzymatic activity (8.2). Comparison of the apoenzyme structure with the one previously determined at pH 6.0 reveals significant differences. The data suggest that the decrease of the enzymatic activity at pH 6.0 may be caused by conformational changes in the active site residues Tyr71, Tyr291, and Arg381 and in the monovalent cation binding residue Glu69. Moreover, at pH 8.0 we observe two different active site conformations: open, which was characterized before, and closed, which is observed for the first time in beta-eliminating lyases. In the closed conformation a significant part of the small domain undergoes an extraordinary motion of up to 12 A toward the large domain, closing the active site cleft and bringing the catalytically important Arg381 and Phe448 into the active site. The closed conformation allows rationalization of the results of previous mutational studies and suggests that the observed active site closure is critical for the course of the enzymatic reaction and for the enzyme's specificity toward its physiological substrate. Finally, the closed conformation allows us to model keto(imino)quinonoid, the key transition intermediate.     

CXCL12 is a costimulator for CD4+ T cell activation and proliferation in chronic lymphocytic leukemia patients

Activated T cells from patients with chronic lymphocytic leukemia (CLL) provide survival and proliferative signals to the leukemic clone within lymphoid tissues. Recruitment of both, CLL cells and T lymphocytes, to this supportive microenvironment greatly depends on CXCL12 production by stromal and myeloid cells. CXCL12 also supplies survival stimuli to leukemic B cells, but whether it exerts stimulatory effects on T lymphocytes from CLL patients is unknown. In order to evaluate the capacity of CXCL12 to increase CD4⁺ T cell activation and proliferation in CLL patients, peripheral blood mononuclear cells were cultured with or without recombinant human CXCL12 or autologous nurse-like cells, and then T cell activation was induced by anti-CD3 mAb. CXCL12 increases the proliferation and the expression of CD25, CD69, CD154, and IFNγ on CD3-stimulated CD4⁺ T cells from CLL patients, similarly in T cells from ZAP-70⁺ to ZAP-70^? patients. Autologous nurse-like cells establish a close contact with CD4⁺ T cells and increase their activation and proliferation partially through a CXCR4-dependent mechanism. In addition, we found that activated T cells in the presence of CXCL12 enhance the activation and proliferation of the leukemic clone. In conclusion, CXCL12 production by lymphoid tissue microenvironment in CLL patients might play a key dual role on T cell physiology, functioning not only as a chemoattractant but also as a costimulatory factor for activated T cells.     

The prevalence of depression and anxiety in seafarers type 2 diabetic patients

Depression and anxiety are co-morbid condition in diabetes as disease-related psychological reactions on this chronic metabolic illness. This study was aimed to determine the occurrence of depression and anxiety in seafarer's type 2 diabetic patients. A random sample of 52 diabetic seafarers treated with diet and oral glucose lowering agents, and 56 healthy seafarers were screened for depression with The Beck Depression Inventory (BDI) and for anxiety with State-Trait Anxiety Inventory (STAI 1, STAI 2). Depression (BDI > 18.5) and anxiety (STAI < 28.5) was significantly higher in the group of diabetic seafarers than in control group (more than 30%). Significant correlation was noted between depression and duration of diabetes mellitus, degree of obesity and poor glycaemic control (HbA1C > 8%) and longer duration of shipping routes (over 6 months). The proportion of depression and anxiety was found higher in seafarer's type 2 diabetic patients than in the healthy seafarers.