Effect of Hydrogen Peroxide and Catalase Derivatives on Functional Activity of Platelets

Effects of H₂O₂ on platelet aggregation were estimated in vitro in the presence and absence of inductors (ADP, serotonin, TRAP) and native and modified catalase. Dose-dependent effect of H₂O₂ (50 μM or more) was investigated in a pathophysiological concentration of 300 μM inducing platelet aggregation. H₂O₂ modulated aggregation induced by ADP, serotonin, and TRAP significantly increasing the initial platelet aggregation followed by disaggregation, which was always more pronounced than in control. Catalase derivatives (native and modified forms) dose-dependently reduced the effect of H₂O₂ and completely abolished it in a dose of 9000 U catalase activity per 1 ml of solution for native catalase and 1200 U/ml for modified one. Modified catalase, in contrast to native one, produced an independent inhibitory effect on induced platelet aggregation. Components of modified catalase (individual substance and simple mixture) had no antiaggregant effect.     

Correlation of Susceptibility and Cytostatic Factor-Inducing Activity of Tumour Cells to Peritoneal Macrophages

L929, 3T12-3, B16, 3LL, and YAC1 cells with cytostatic factor (CF)-inducing activity from Lactobacillus casei-elicited murine peritoneal macrophages (LCEPM) were susceptible to the cytostatic activity of LCEPM and to LCEPM-produced CF, but L1210, P388D1, and Colon 26 cells, which have no CF-inducing activity, were resistant to that of LCEPM and and to the CF. The resistance of P815 cells to that of LCEPM was stronger than that of 3T12-3 cells, but the CF-inducing activity of P815 cells was about 50% weaker than that of 3T12-3 cells. Release of CF from LCEPM was also caused by heat-killed (100 degrees C, 10 min) 3T12-3 or P815 cells, and this release was inhibited by D-mannose. The CF-inducing activity of heat-killed 3T12-3 or P815 cells was reduced by mild trypsin digestion (37 degrees C for 10 min). A D-mannose-containing glycopeptide or glycoprotein (GP) was separated from 3T12-3 or P815 cells by concanavalin A (Con A) or wheat germ agglutinin (WGA) affinity chromatography. The CF were released from LCEPM by stimulation with the Con A-binding GP of the tumour cells, but the WGA-binding GP had little activity. It is suggested that tumour cells with CF-inducing activity may be susceptible to the cytostatic activity of LCEPM, and those without CF-inducing activity may be resistant to the cytostatic activity of LCEPM and the release of CF from activated macrophages may be caused by the Con A-binding GP of the tumour cell surface.     

外源几丁质酶对致倦库蚊的毒杀作用及其与二元毒素的协同杀蚊作用

目的研究几丁质酶对蚊幼虫的毒力、后致死作用及对二元毒素的协同杀蚊作用。方法提取粘质沙雷氏菌S3菌株的几丁质酶和球形芽胞杆菌C3-41菌株的二元毒素,通过浸渍法处理致倦库蚊2～3龄幼虫48 h。结果几丁质酶对致倦库蚊幼虫具有低毒,其LC50和LC90分别为8.99和28.5μg/ml;且对抗性库蚊的毒力与敏感幼蚊相当,其LC50和LC90分别为11.9、168μg/ml。几丁质酶对致倦库蚊幼虫还具有一定程度的后致死作用,不同亚致死浓度的几丁质酶处理后的存活幼虫均出现不同程度的延续死亡。几丁质酶与二元毒素共同作用于敏感致倦库蚊幼虫时,几丁质酶表现出明显的对二元毒素的增效作用,LC2、LC10、LC30剂量（1.59、2.84和5.61μg/ml）的几丁质酶分别能使二元毒素的毒力增强1.98、3.53和8.11倍,其增效作用随几丁质酶剂量的增加而增强。结论几丁质酶对致倦库蚊幼虫具有低毒及一定的后致死作用,其与二元毒素合用具有增效作用,在蚊虫防治方面具有较大的开发前景。     

NOS2 Variants Reveal a Dual Genetic Control of Nitric Oxide Levels,Susceptibility to Plasmodium Infection,and Cerebral Malaria

Nitric oxide (NO) is a proposed component of malaria pathogenesis, and the inducible nitric oxide synthase gene (NOS2) has been associated to malaria susceptibility. We analyzed the role of NOS2 polymorphisms on NO bioavailability and on susceptibility to infection, Plasmodium carrier status and clinical malaria. Two distinct West African sample collections were studied: a population-based collection of 1,168 apparently healthy individuals from the Príncipe Island and a hospital-based cohort of 269 Angolan children. We found that two NOS2 promoter single-nucleotide polymorphism (SNP) alleles associated to low NO plasma levels in noninfected individuals were also associated to reduced risk of pre-erythrocytic infection as measured anti-CSP antibody levels (6.25E–04 < P < 7.57E–04). In contrast, three SNP alleles within the NOS2 cistronic region conferring increased NO plasma levels in asymptomatic carriers were strongly associated to risk of parasite carriage (8.00E–05 < P < 7.90E–04). Notwithstanding, three SNP alleles in this region protected from cerebral malaria (7.90E–4 < P < 4.33E–02). Cohesively, the results revealed a dual regimen in the genetic control of NO bioavailability afforded by NOS2 depending on the infection status. NOS2 promoter variants operate in noninfected individuals to decrease both NO bioavailability and susceptibility to pre-erythrocytic infection. Conversely, NOS2 cistronic variants (namely, rs6505469) operate in infected individuals to increase NO bioavailability and confer increased susceptibility to unapparent infection but protect from cerebral malaria. These findings corroborate the hypothesis that NO anti-inflammatory properties impact on different steps of malaria pathogenesis, explicitly by favoring infection susceptibility and deterring severe malaria syndromes.     

Salivary Nitrate,Nitrite and Nitrate Reductase Activity in Relation to Risk of Oral Cancer in Egypt

It has been suggested that nitrate and nitrite may play a role in the etiology of human oral cancer. We investigated whether salivary nitrate and nitrite and the activity of nitrate reductase (NRase) may affect the risk of oral cancer in Egypt, an area with high levels of environmental nitrosating agents. Levels of salivary nitrite (8.3 ± 1.0 μg/ml) and nitrate (44 ± 3.7 μg/ml) and activity of NRase (74 ± 10 nmol/ml/min) were significantly (P < 0.05) higher in oral cancer patients (n = 42) compared to control Egyptian healthy individuals (n = 40, nitrite = 5.3 ± 0.3 μg/ml, nitrate = 27 ± 1.2 μg/ml, and NRase activity = 46 ± 4 nmol/ml/min). The adjusted odds ratio (OR) and the 95% confidence intervals (C.I.) for risk of oral cancer, categorized by the levels of salivary nitrate and nitrite and NRase activity, showed a higher cancer risk associated with nitrite > 7.5 μg/ml (OR: 3.0, C.I.: 1.0–9.3), nitrite > 40 μg/ml (OR: 4.3, C.I.: 1.4–13.3) and NRase activity > 50 nmol/ml/min (OR: 2.9, C.I.: 1.1–7.4). Our findings suggest that increased consumption of dietary nitrate and nitrite is associated with elevated levels of salivary nitrite. Together with the increased activity of salivary NRase, these observations may explain, at least in part, the role of nitrate and nitrite in the development of oral cancer in individuals from an area with a high burden of N-nitroso precursors.     

Levels of Spontaneous Activity and Spike Responses of Cortical Neurons to Local Administration of Excitatory Amino Acids to Their Dendrites and Bodies

Studies of cortical cortex slices showed that spontaneous neuron activity depended on the conditions of transmission of excitation from dendrites to the body. Studies using a measure of the efficiency of dendrosomatic conduction showed that cortical neurons constituted a significantly heterogeneous population. Spike reactions to direct excitation of cell bodies were relatively stable in neurons with different levels of spontaneous activity. Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 94, No. 5, pp. 502–511, May, 2008.     

Lipopolysaccharide-Deficient Acinetobacter baumannii Shows Altered Signaling through Host Toll-Like Receptors and Increased Susceptibility to the Host Antimicrobial Peptide LL-37

Infections caused by multidrug-resistant Acinetobacter baumannii have emerged as a serious global health problem. We have shown previously that A. baumannii can become resistant to the last-line antibiotic colistin via the loss of lipopolysaccharide (LPS), including the lipid A anchor, from the outer membrane (J. H. Moffatt, M. Harper, P. Harrison, J. D. Hale, E. Vinogradov, T. Seemann, R. Henry, B. Crane, F. St. Michael, A. D. Cox, B. Adler, R. L. Nation, J. Li, and J. D. Boyce, Antimicrob. Agents Chemother. 54:4971–4977, 2010). Here, we show how these LPS-deficient bacteria interact with components of the host innate immune system. LPS-deficient A. baumannii stimulated 2- to 4-fold lower levels of NF-κB activation and tumor necrosis factor alpha (TNF-α) secretion from immortalized murine macrophages, but it still elicited low levels of TNF-α secretion via a Toll-like receptor 2-dependent mechanism. Furthermore, we show that while LPS-deficient A. baumannii was not altered in its resistance to human serum, it showed increased susceptibility to the human antimicrobial peptide LL-37. Thus, LPS-deficient, colistin-resistant A. baumannii shows significantly altered activation of the host innate immune inflammatory response.     

Antibody Response to Achromobacter xylosoxidans during HIV Infection Is Associated with Lower CD4 Levels and Increased Lymphocyte Activation

Inflammation during HIV infection is associated with worse disease outcomes and progression. Many mechanisms have been indicted, including HIV itself, coinfections, and gut microbial translocation. Concerning microbial translocation, we hypothesized that adaptive immune responses to a specific bacterial species known to be present in gut-associated lymphoid tissue are higher among HIV-infected individuals than among HIV-uninfected controls and are associated with T cell activation and lower CD4 T cell counts. By characterizing the IgG response to Achromobacter xylosoxidans, we found that HIV-infected participants who were immunoresponsive (n = 48) had significantly lower CD4 percentages (P = 0.01), greater CD4 activation (percentages of RA⁻ CD38⁺) (P = 0.03), and higher soluble CD14 (P = 0.01). HIV-positive individuals had higher anti-A. xylosoxidans IgG titers than HIV-uninfected individuals (P = 0.04). The results suggest an abnormal adaptive immune activation to gut microflora during HIV infection.     

Cooperative Activity of Neurons in the Nucleus Accumbens and Frontal Cortex in Cats Trained to Select Reinforcements of Different Value

Results obtained at the level of the organization of interneuronal interactions of cells in the nucleus accumbens and frontal cortex revealed the features of the involvement of this component in “impulsive” and “self-controlled” behavior, consisting of an increase in bidirectional interactions between the structures of interest, accompanied by simultaneous reductions in the regularity of interactions with increases in “impulsivity” and decreases in “self-control.” Long-latency reactions appearing only in “impulsive” animals were associated with decreases in the control of frontal cortex cells by the nucleus accumbens during the signal period, which correlated with the low activity of the network activity of the nucleus accumbens in these animals. Comparison of the patterns of frontal-accumbens interactions as the animals performed a single type of activity demonstrated that the connections in neuron pairs during the presignal and signal periods were similar, while significant differences in patterns were seen during the performance of different types of activity.     

Activity of Neurons in the Mouse Inferior Colliculus in Relation to the Position and Direction of Displacement of Spectral Contrast

The variability of the responses of neurons in the inferior colliculus of the mouse (Mus musculus) to sequences of signals of noise bands and wide-band noise with spectral notches with regular changes (by 1/12 octave) in the central band frequency or notch frequency was studied. When the width of spectral changes was 1/3 octave, neurons with strong inhibitory influences in the excitatory zone of the response ("inhibition-dependent" neurons) showed low levels of spike activity if the noise band completely covered the excitatory part of the response. The most effective stimuli for these neurons were spectral contrasts passing through the center of the excitatory part of the response (through or close to the characteristic frequency). The responses of neurons to spectral contrasts created by noise bands and noises with notches were identical. It is suggested that approximation of the inhibitory and excitatory inputs sharpens the frequency tuning of neurons to the position of the spectral contrasts, as occurs in the visual system. The selectivity of neurons to the direction of moving spectral contrasts is manifest as a difference in responses when they move from the excitatory area of the response to the inhibitory and vice versa. The functional significance of the contrast mechanism for the analysis of sound source movement based on direction-dependent spectral features associated with the transfer characteristics of the external ear is discussed.     

Increased Susceptibility of Tumor Cells and Chicken Erythrocytes to Lysis by Antibody and Complement after Treatment with Aminoethylisothiouronium Bromide Hydrobromide (AET)

After treatment with aminoethylisothiouronium bromide hydrobromide (AET), the ascites forms of the diethylnitrosamine-induced guinea pig hepatomas, line-1 and line-10, were susceptible or more susceptible to killing in vitro by certain combinations of tumor-specific or IgM anti-Forssman antibody and either human or guinea pig complement. Since AET could be toxic to either cell line, conditions of pH, concentration of AET, and duration of exposure of the cells to the reagent were determined that resulted in enhanced susceptibility without significantly affecting cell viability. Chicken erythrocytes (CE) also were tested and AET-treated cells found to be more susceptible to lysis by IgM anti-Forssman antibody and guinea pig complement. The enhancement apparently was not due to increased ability of AET-treated CE to fix antibody. In contrast to CE, the lytic susceptibility of sheep cells was not affected by AET treatment. In addition to AET, several drugs and enzymes that also can affect the susceptibility of the tumor cells to antibody and complement were tested and found to be ineffective against CE.

Since AET reputedly acts directly on the cell surface, it seems reasonable to assume that the increased susceptibility of the tumor cells and CE to antibody and complement may result from a modification of the cell surface.     

Analysis of the Effects of Antibodies to Gangliosides on the Electrical Activity of Retzius Neurons in the Leech and on the Functional Activity of Influx Sodium Current Channels

The effects of anti-ganglioside antibodies on the functional states of two types of influx Na+ current channels were studied. Experiments used 20% anti-ganglioside antiserum prepared by standard methods by immunizing rabbits with total bovine brain gangliosides. These experiments showed that incubation of neurons in physiological saline containing antiserum induced discordance in the operation of the two types of influx current Na+ channels responsible for spike generation. This reaction was found to be associated with the slowed rate of activation of TTX-sensitive Na+ channels. Synaptic stimulation of cells in the presence of antiserum induced blockade of TTX-insensitive influx Na+ current channels. High-frequency synaptic activation of cells (10 Hz) showed that apart from blockade of TTX-insensitive Na+ channels, anti-ganglioside antibodies prevented plastic rearrangements in the gate system of TTX-sensitive Na+ channels. This resulted in impairment of the development of the acclimation process - the response of the neuron to high-frequency stimulation seen in normal conditions.     

Defect of CARD9 Leads to Impaired Accumulation of Gamma Interferon-Producing Memory Phenotype T Cells in Lungs and Increased Susceptibility to Pulmonary Infection with Cryptococcus neoformans

Caspase recruitment domain-containing protein 9 (CARD9) is an adaptor molecule signal that is critical for NF-κB activation and is triggered through C-type lectin receptors (CLRs), which are pattern recognition receptors that recognize carbohydrate structures. Previous studies have reported that Cryptococcus neoformans, a fungal pathogen that causes meningoencephalitis in AIDS patients, is recognized through some CLRs, such as mannose receptors or DC-SIGN. However, the role of CARD9 in the host defense against cryptococcal infection remains to be elucidated. In the present study, we analyzed the role of CARD9 in the host defense against pulmonary infection with C. neoformans. CARD9 gene-disrupted (knockout [KO]) mice were highly susceptible to this infection, as shown by the reduced fungal clearance in the infected lungs of CARD9 KO mice, compared to that in wild-type (WT) mice. Gamma interferon (IFN-γ) production was strongly reduced in CARD9 KO mice during the innate-immunity phase of infection. Reduced IFN-γ synthesis was due to impaired accumulation of NK and memory phenotype T cells, which are major sources of IFN-γ innate-immunity-phase production; a reduction in the accumulation of these cells was correlated with reduced CCL4, CCL5, CXCL9, and CXCL10 synthesis. However, differentiation of Th17 cells, but not of Th1 cells, was impaired at the adaptive-immunity phase in CARD9 KO mice compared to WT mice, although there was no significant difference in the infection susceptibility between interleukin 17A (IL-17A) KO and WT mice. These results suggest that CARD9 KO mice are susceptible to C. neoformans infection probably due to the reduced accumulation of IFN-γ-expressing NK and memory phenotype T cells at the early stage of infection.     

Genetic Resistance of Mice to Persistent Infection with Mycobacterium Lepraemurium in Vitro: Association with Macroprage Bactericidal Responsiveness to Lymphokines and Dissociation from Production of Hydrogen Peroxide by Macrophages

Peritoneal and splenic adherent macrophages (SAC) from M. lepraemurium susceptible (C3H/HeJ) and resistant (C57B1/6J) mice were studied for their abilities to generate H₂O₂ in vitro. Unexpectedly, SAC from the susceptible C3H/HeJ strain produced more H₂O₂ than hose of the resistant C57BL/6J. In vivo sensitization with M. bovis (BCG), or C. parvum increased production of H₂O₂ by SAC from both strains, whereas in vivo sensitization with M. leraemurium enhanced H₂O₂ production only in the C3H/HeJ susceptible strains. In vitro addition of a crude lymphokine enhanced H₂O₂ production by C3H/HeJ SAC more than by C57BL/6J SAC. In vitro addition of M. lepraemurium caused an inhibition of H₂O₂ production by SAC from both strains but the inhibition was greater for the resistant C57BL/6J strain. M. leraemurium phagocytosed in vitro by untreated peritoneal macropbages of both mouse strains were morphologically altered to the aame extent. However, the addition of lymphokine dramatically increased the degree of bacterial lysis in only the C57BL/6J strain. These results, support the view that H₂O₂ plays a limited. if any, role in the protection of the host from M. lepraemurium and may even contribute to susceptibility by inhibiting the host's immune response.     

Comparative Analysis of Spike Activity of Neurons in Hippocampal Field CA1 and CA3 in Rats of Different Typological Groups on Exposure to Emotional Stimuli

Spike activity from neurons in hippocampal field CA1 and CA3 was compared in rats avoiding (“altruists,” group A) and not avoiding (“egoists,” group E) the cries of a “victim” partner on testing using the emotional resonance method. Neuron discharge frequencies were compared in animals in the state of starvation, after satiation, and on exposure to emotionally positive and negative intracerebral electrical stimuli. These studies showed that hippocampal field CA1 was dominated by cells increasing their spike frequencies after satisfaction of the food motivation, while in field CA3, conversely, most cells decreased activity after eating. Exposure to emotionally significant stimuli identified interhemisphere differences in the activities of hippocampal neurons which were associated with the typological characteristics of the animals. In rats of group A, neurons in field CA1 were activated only in the left hippocampus, while the activity of cells in the right hippocampus was no different from that in baseline conditions. Field CA3 of rats of this group showed no asymmetry. In rats of group E, conversely, lateralization of activity was seen only in field CA3: discharge frequencies were significantly greater in the left hippocampus.     

Correlation of Increased Metabolic Activity, Resistance to Infection, Enhanced Phagocytosis, and Inhibition of Bacterial Growth by Macrophages from Listeria- and BCG-Infected Mice

Macrophages from mice infected with facultative intracellular organisms such as Listeria monocytogenes and BCG have been shown to resist infection by antigenically unrelated intracellular bacterial parasites. This study compares phagocytosis, bacterial growth inhibition, and oxidation of glucose by macrophages from normal mice, mice infected with listeria or BCG, or mice immunized with killed listeria in incomplete Freund's adjuvant. Macrophages from listeria- and BCG-infected mice ingested more listeria; 67 and 57%, respectively, had three or more cell-associated bacteria versus 22% of controls (P < 0.001). Peritoneal macrophages from listeria- and BCG-infected animals significantly (P < 0.001 covariance analysis) inhibited growth of listeria in suspension, whereas control macrophages had no such inhibitory effect. The rate of oxidation of glucose-1-(14)C was higher in macrophages from listeria- and BCG-infected mice than from either uninfected animals or those immunized with killed listeria. During phagocytosis of killed or live bacteria, or latex particles, the rate of glucose oxidation was increased (P < 0.01). These data suggest that the cellular immunity after infection by an intracellular organism is associated with an increase in metabolic activity of macrophages, namely, an increase in the rate of glucose oxidation resulting in enhancement of phagocytosis and killing.     

Effects of Cadmium Exposure on the Ultrastructural Pathology of Different Pulmonary Cells,Leukocyte Count,and Activity of Glutathione Peroxidase and Lactate Dehydrogenase in Relation to Free Radical Production in Uromastyx aegyptius

Animal studies on the toxicity of heavy metals have been widely used as model to simulate the impacts of environmental pollution on the human health. In the present study the authors hypothesized that cadmium exposure inducts changes in reactive oxygen species (ROS) and that may be involved in the pathogenesis of lung diseases. The pathological changes of different pulmonary cells of ROS-cadmium-dependent effects were investigated in relation to the activity of lactate dehydrogenase (LDH) and glutathione peroxidase (GPx). Twelve animals were randomly assigned to two groups, control and experimental. The experimental group underwent ingestion of cadmium mixed with diet (200?mg/kg) for 7 weeks. Following the treatment conditions for each group, blood samples were collected and animals were sacrificed and the lung was isolated. Ultrastructure examination showed that cadmium resulted in desquamated pneumocyte type II with degenerated surfactant materials, thickened alveolar wall, and thickening of alveolar septum due to proliferation of endothelial cells lining the pulmonary capillaries as a result of an active transmigration. t-test results showed that cadmium caused a significant (p < .05) rise in leukocytes, lymphocytes, neutrophils, and monocytes, which was a sign for chemotactic activity that enhanced transmigration from pulmonary microcirculation into inflammated tissue. In addition, lung tissue FR production, LDH, and GPx activities increased significantly (p < .05) from the baseline control of 88.17±17.70, 183.49±29.50, and 4466.79±1190.32 to 129.67±14.49.14 (Carr U), 339.17±75.28 (U/L), and 5943.08±695 (U/L) respectively, in the cadmium-treated group. Based on the results of the present study, it can be concluded that long-term cadmium exposure (ingestion mixed with food) results in cadmium deposition in the tissue of the vasculature of the lungs, such as pulmonary capillary endothelial, which induced the buildup of ROS, a possible proposed new mechanism that explains lung inflammation.