Effect of immature Schistosoma mansoni worms on hamsters' plasma enzymes

1. The pattern and activity of isocitrate, lactate and malate dehydrogenases and malic enzyme were studied in plasma of normal hamsters and hamsters at the 26th day of infection with S. mansoni. 2. Although the electrophoretic patterns of these enzymes were similar in normal and infected hamsters, their activities were higher in the latter than the former group of animals. The elevation in the enzymic activity indicates that there is tissue damage caused by the larvae at this stage.     

Channa punctata brain metallothionein is a potent scavenger of superoxide radicals and prevents hydroxyl radical-induced in vitro DNA damage

Mammalian brain metallothioneins (MTs) have been shown to scavenge free radicals. However, a similar role for fish brain MT has not been established yet. Previously, we have reported that MT from the liver of a freshwater fish, Channa punctata Bloch, had free-radical-scavenging activity in vitro. In this study, we report on the induction of MT in brain and other tissues of C. punctata treated with a low concentration of zinc chloride. We partially purified MT (Zn-MT)-rich fraction from the brain and studied its free-radical-scavenging and DNA damage attenuating effects. Zinc exposure showed significant MT induction in brain, gill, kidney, and liver. C. punctata brain MT efficiently scavenged superoxide radicals and also attenuated hydroxyl radical-mediated DNA damage. These findings suggest that fish brain MT has a free-radical-scavenging activity, and its expression may be regulated in response to stress and chemical exposure. C. punctata has been identified as a potent biomarker fish species. It is suggested that this fish species may be a good model for the study of MTs with regard to their regulatory and biomarker functions.     

Beta-sheet capping: signals that initiate and terminate beta-sheet formation

In the present work, we address the question of whether different amino acids have different beta-sheet initiating and terminating characteristics. Using a large scale analysis of parallel and antiparallel beta-sheets in a non-redundant dataset of proteins, we observed that most of the amino acids show significant under- or over-representation in at least one of the positions at the two ends of beta-sheets, which are denoted as N-cap and C-cap. In addition, based on statistical data and structural comparison, we found that certain amino acids, especially Asp, Asn, Gly and Pro have strong tendencies to block beta-sheet continuation. Hence, we can consider these residues as beta-sheet terminators. It was also proposed that the dipole moments in parallel beta-sheets, whose direction is from C-terminal (partially negative) to N-terminal (partially positive), are much stronger than has previously been suggested. In fact, enhancement of dipole moments in parallel beta-sheets is a result of the positioning of positively charged residues at N-cap and negatively charged residues at C-cap. This enhancement in dipole moment magnitude leads to strengthened dipolar interactions between parallel beta-sheets dipoles and other partners especially alpha-helices dipoles. The results provide an explanation for the antiparallel alignment of parallel beta-sheets with alpha-helices.     

Influence of influenza viral infection on airway smooth muscle activity

The contractility of airway smooth muscle (ASM) plays an important role in pathophysiology of several bronchial disorders. Increased contraction of ASM during asthma and respiratory viral infection has been attributed to the release of mediators acting through different receptors. In the present study, influence of influenza type A virus (H1N1) infection has been examined on ASM responsiveness to various bronchoactive agents e.g. adenosine, histamine, 5-hydroxytryptamine (5-HT) and isoproterenol in an organ bath set up for isolated tissue preparation. The contractile effect of adenosine, histamine and 5-HT was enhanced, however, relaxant response of isoproterenol was attenuated with the duration following viral exposure. The most prominent response was observed 48 to 72 hr after infection and tissues from multiple exposure to virus infected animals showed the maximum contractile response. Results demonstrated the deleterious effect of viral infection on ASM function and the findings will be helpful in understanding the mechanism of influenza virus induced bronchoconstriction.     

Alpha tocopherol protects against immunosuppressive and immunotoxic effects of lead

Chronic exposure to lead (Pb) is associated with multiorgan toxicity. The precise mechanism(s) involved, however, remains incompletely defined. The present study was undertaken to analyze the effect of Pb on the immune system and determine the ability of alpha tocopherol (AT) to reverse Pb-induced immunotoxicity. Groups of TO Mice (6 per group) were treated ip for 2 weeks with saline alone, Pb acetate alone, Pb plus AT, or with AT alone. Spleens were then analyzed for (i) cellular composition by flow cytometry, (ii) cellular response to B and T cell mitogens and (iii) production of nitric oxide (NO). Pb treatment resulted in a significant state of splenomegaly associated mainly with an influx of CD11b+ myeloid cells. Surprisingly, however, these cells exhibited no upregulation in expression of activation markers and did not produce NO. The lymphocyte mitogenic responses were inhibited by > or = 70% in Pb-treated group. Concurrent treatment with Pb and AT resulted in almost a complete reversal of Pb-induced splenic cellular influx. Despite this, however, mitogenic responses in Pb + AT treated group were approximately 50% of those observed in normal (saline-treated) controls. We conclude that (1) chronic treatment with Pb acetate induces a state of splenomegaly and decreased proliferation in response to mitogenic stimuli and (2) co-treatment with AT largely reversed the cellular influx but this was associated with only a partial improvement of the mitogenic responses. These results highlight the role of AT as a potentially effective antioxidant in the immune system.     

Antitumor activities of iodoacetate and dimethylsulphoxide against solid Ehrlich carcinoma growth in mice

Treatment of tumor-bearing mice with LD12.5 values of iodoacetate; IAA (1.84 mg/100 g b.w.) and/or dimethylsulphoxide; DMSO (350 mg/100 g b.w.) significantly increased the cumulative mean survival time and percentage of survivors and reduced the mean tumor weight, compared to tumor-bearing controls, however, a more pronounced effect is recorded in the combined treatment. Also, an increase in the life span (ILS%) and tumor growth inhibition ratio (T/C%) are reported and amounted to 145.78 and 43.80%, 195.54 and 61.30% and 220.77 and 78.40% in IAA, DMSO and combined-treated groups, respectively. Results obtained from biochemical studies reveal that a single IAA treatment of tumor-bearing mice significantly increased the levels of plasma lactate dehydrogenase (LDH) activity, while it also significantly decreased the levels of plasma glucose and liver total protein, RNA and DNA, compared to normal controls. On the other hand, a single DMSO treatment significantly elevated the activities of blood antioxidant enzymes, i.e. glutathione peroxidase (GPx) and glucose-6-phosphate dehydrogenase (G6PDH) and decreased the liver RNA and DNA levels. Combined treatment increased significantly the levels of plasma LDH and erythrocytes G6PDH activities, as well as liver glycogen, and in contrast it decreased the levels of liver total protein, RNA and DNA, compared to normal controls.     

alpha-Tocopherol modifies lead induced functional changes at murine neuromuscular junction

Lead impacts neuromuscular junction and might induce skeletal muscle weakness. Antioxidants may prevent toxic actions of lead on muscle. In this study, resting membrane potentials, endplate potentials, miniature endplate potentials (MEPPs) and isometric twitch tensions were recorded to investigate effects of alpha-tocopherol (Vitamin E) on lead induced changes at murine dorsiflexor muscle. Moreover, levels of endplate nicotinic receptors were measured by receptor autoradiography. Forty rats were divided into four groups (lead alone, alpha-tocopherol, lead plus alpha-tocopherol and saline). Lead (1 mg/kg, i.p.), was administered daily for 2 weeks and alpha-tocopherol (100 mg/kg, i.p.) was given daily for 3 weeks. Lead treatment significantly reduced twitch tension (from 4.4+/-0.4 to 2.2+/-0.3 g) and delayed half time of decay. MEPP frequencies and quantal content were also significantly reduced after lead treatment. Pretreatment with alpha-tocopherol reversed twitch tension reduction (4.1+/-0.3 g) and modified lead induced delay in half time of decay. Similarly, alpha-tocopherol modified the negative actions of lead exposure on MEPP frequencies and quantal content. Receptor autoradiographic studies revealed significant increase of nicotinic receptor levels at the endplate region of flexor muscle in lead treated mice. However, animals treated with lead plus alpha-tocopherol showed significantly decreased levels of nicotinic receptors. alpha-Tocopherol appears to protect against lead induced neuromuscular dysfunction. These effects of alpha-tocopherol are possibly mediated via a free radical mechanism or modification of calcium homeostasis.     

A new EPR dosimeter based on glutamic acid for radiation processing application

Radiation and Environmental Biophysics - l-Glutamic acid (L-GA) pellets (3.8 mm × 4 mm) and powder dosimeters were studied in the dose range of...