The immunomorphological characteristics of a focal staphylococcal infection against a background of long-term exposure to low doses of simazine]

State of immunologic and nonspecific resistance of the organism, ultra- and histostructure of the thymus, histopathology of the wall of experimental staph abscess reproduced in animals given low doses of the herbicide simazine for a long time have been studied. It is established that simazine induced the immunodeficiency state underlain by pathologic changes in the thymus. Against this background experimental abscesses developed more rapidly, alterative and exudative processes in their wall proceeding more intensively and proliferative ones--attenuating. This provides prolongation of the abscesses healing phase for an indefinite time and chronization of the process.     

The mast cell reaction to a staphylococcal infection occurring against a background of immunodeficiency after cyclophosphane administration

Materials on the study of the morphofunctional state of mast cells in mouse in experimental staphylococcal infection under the conditions of cyclophosphamide-induced immunodeficiency are presented. As revealed in this study, the infectious process developing in the presence of immunodeficiency is accompanied by the profound and prolonged suppression of the morphofunctional status of mast cells and natural immunity factors at the peak of the disease.     

An immunological approach to the conformational equilibrium of staphylococcal nuclease.

The conformational equilibrium constant, K_conf, of staphylococcal nuclease, describing the equilibrium between the native conformation and non-native or disordered conformations, has been estimated using an immunologic method and an interpretive model. Using goat antisera prepared toward a conformationally disordered nuclease fragment (99–149), antibodies specific for the disordered form of the helix-rich sequence 99 to 126, anti-(99–126)_R, were isolated by sequential immunoabsorption. Anti-(99–126)_R forms soluble 7 S complexes with fragment (99–149), but this interaction may be inhibited by a large excess of nuclease. By using fragment (99–149) preferentially carbamylated at the α-amino terminus with KN¹⁴CO and rabbit anti-goat immunoglobulin to distinguish between antibody-bound and free fragment (99–149), an assay for the quantitation of the degree of inhibition of anti-(99–126)_R. (99–149) complex formation by nuclease was developed.Using a formal analysis based on the hypothesis that nuclease is in a conformational equilibrium between a folded and unfolded form and that anti-(99–126)_R binds effectively only to the unfolded form, the K_conf of nuclease was estimated to be 2900. In the presence of the ligands Ca(II), or Ca(II) and thymidine-3′,5′-diphosphate, K_conf values of 6500 and 30,000 to 50,000 were estimated, respectively. The K_conf of nuclease at 4 °C and 39 °C was 3900 and 400, respectively.     

Protection against focal cerebral ischemia following exposure to a pulsed electromagnetic field

There is evidence that electromagnetic stimulation may accelerate the healing of tissue damage following ischemia. We undertook this study to investigate the effects of low frequency pulsed electromagnetic field (PEMF) exposure on cerebral injury in a rabbit model of transient focal ischemia (2 h occlusion followed by 4 h of reperfusion). PEMF exposure (280 V, 75 Hz, IGEA Stimulator) was initiated 10 min after the onset of ischemia and continued throughout reperfusion (six exposed, six controls). Magnetic resonance imaging (MRI) and histology were used to measure the degree of ischemic injury. Exposure to pulsed electromagnetic field attenuated cortical ischemic edema on MRI at the most anterior coronal level by 65% (P < 0.001). On histologic examination, PEMF exposure reduced ischemic neuronal damage in this same cortical area by 69% (P < 0.01) and by 43% (P < 0.05) in the striatum. Preliminary data suggest that exposure to a PEMF of short duration may have implications for the treatment of acute stroke. © 1994 Wiley-Liss, Inc.     

Architecture and spatial organization in a triple-species bacterial biofilm synergistically degrading the phenylurea herbicide linuron

Members of a triple-species 3-(3,4-dichlorophenyl)-1-methoxy-1-methyl urea (linuron)-mineralizing consortium, i.e. the linuron- and 3,4-dichloroaniline-degrading Variovorax sp. WDL1, the 3,4-dichloroaniline-degrading Comamonas testosteroni WDL7 and the N,O-dimethylhydroxylamine-degrading Hyphomicrobium sulfonivorans WDL6, were cultivated as mono- or multi-species biofilms in flow cells irrigated with selective or nonselective media, and examined with confocal laser scanning microscopy. In contrast to mono-species biofilms of Variovorax sp. WDL1, the triple-species consortium biofilm degraded linuron completely through apparent synergistic interactions. The triple-species linuron-fed consortium biofilm displayed a heterogeneous structure with an irregular surface topography that most resembled the topography of linuron-fed mono-species WDL1 biofilms, indicating that WDL1 had a dominating influence on the triple-species biofilm architecture. This architecture was dependent on the carbon source supplied, as the biofilm architecture of WDL1 growing on alternative carbon sources was different from that observed under linuron-fed conditions. Linuron-fed triple-species consortium biofilms consisted of mounds composed of closely associated WDL1, WDL7 and WDL6 cells, while this association was lost when the consortium was grown on a nonselective carbon source. In addition, under linuron-fed conditions, microcolonies displaying associated growth developed rapidly after inoculation. These observations indicate that the spatial organization in the linuron-fed consortium biofilm reflected the metabolic interactions within the consortium.     

Constitutive mineralization of low concentrations of the herbicide linuron by a Variovorax sp. strain

The mineralization of the herbicide linuron at concentrations of μg and mg L⁻¹ was studied in liquid batch experiments with Variovorax sp. strain SRS16. The strain was highly efficient at mineralizing a range of linuron concentrations (0.002–10 mg L⁻¹) with 20–60% of the added ¹⁴C-ring-labeled linuron metabolized to ¹⁴CO₂ within hours to days depending on the initial linuron concentration and incubation period. At mg L⁻¹ linuron concentrations the mineralization activity by SRS16 was inducible and a shift to constitutive mineralization activity was apparent with a reduction in the linuron concentration to μg L⁻¹ levels. This study revealed that strain SRS16 is a promising candidate for bioaugmentation of water or soil resources contaminated with low linuron concentrations.     

Bone marrow cells as affected by staphylococcal toxin against a background of overheating of the whole body

The electron microscopic study of the material demonstrates that after injection of staphylococcal toxin in combination with high temperature, in the bone marrow cells of the animals certain ultrastructural changes are observed already from the first day of the experiment and they progressively increase. Especially essential changes are observed in the cells of erythroid and granulocytic sprouts. In elements of lymphoid and megakaryocytic sprouts morphological changes are manifested to a less degree. Sometimes in vacuoles irregular formations of high electron density are localized.     

Epidemiological and immunological study of the foci of measles infection

Anamnestic data in respect to measles failed to correspond to the results of serological examination of contacts at the foci of the given infection. The collective immunity level in children's institutions is inadequate for the prevention of measles outbreaks. The incidence of the disease depended both on the level of immunity among the children and on the duration of presence of the source of infection in the focus. Live measles vaccine protected 90 percent of the vaccinated children from contracting the disease in the foci. At the very beginning of the postvaccinal period immunization defects were revealed in 26.5 percent of the vaccinated children who fell ill with measles. Morbidity index among the vaccinated individuals constituted 3.8 percent. One of the causes of measles contraction by the vaccinated individuals was the loss of postvaccinal immunity. Systematic control over the antimeasles immunity level with the aid of serological investigations is necessary for the purpose of detection of persons sensitive to measles in children's collective bodies.     

A morphological study of uterine alterations in mice due to exposure to cadmium

We investigated the morphologic and molecular effects of exposure to cadmium (Cd) for 30 and 60 days on the uteri of mice. We assessed uterine morphometric measurements, eosinophilia, mast cell numbers, endometrial apoptosis, proliferation and estrogen receptor alpha (ERα) immunoreactivity. We examined vaginal smears that reflected the hormonal alterations in the female reproductive tract. Because the female reproductive tract exhibits different morphology at each stage of the estrous cycle, we sacrificed all animals at estrus to make appropriate comparisons. Female BALB/c mice were exposed to 200 ppm Cd in their drinking water for either 30 or 60 days. Cd exposure caused significant decreases in endometrial thickness and number of glands in estrus phase uteri. The endometrial eosinophilia in the groups exposed to Cd also decreased compared to controls. Cd exposure increased the number of mast cells. Luminal and glandular epithelia were examined using the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and by immunostaining proliferating cell nuclear antigen (PCNA) and estrogen receptor α (ERα). Compared to controls, the apoptotic index increased with time in both Cd exposed groups, while the proliferation index decreased. ERα immunoreactivity was decreased in both Cd exposed groups compared to controls; the decrease was most apparent in the 30 day Cd group. We found that 60 day Cd exposure increased apoptosis in the endometrium, which may affect the receptivity of the uterus for implantation.     

Inhibition of photosystem II (PSII) electron transport as a convenient endpoint to assess stress of the herbicide linuron on freshwater plants

Effects of the herbicide linuron on photosynthesis of the freshwater macrophytes Elodea nuttallii (Planchon) St. John, Myriophyllum spicatum L., Potamogeton crispus L., Ranunculus circinatus Sibth., Ceratophyllum demersum L. and Chara globularis (Thuill.), and of the alga Scenedesmus acutus Meyen, were assessed by measuring the efficiency of photosystem II electron flow using chlorophyll fluorescence. In a series of single-species laboratory tests several plant species were exposed to linuron at concentrations ranging from 0 to 1000 μg l−1. It was found that the primary effect of linuron, inhibition of photosystem II electron flow, occurred with a half-lifetime of about 0.1 to 1.9 h after addition of linuron to the growth medium. The direct effect of the herbicide on photosynthesis appeared to be reversible. Complete recovery from the inhibition occurred with a half-lifetime of 0.5 to 1.8 h after transfer of linuron treated plants to linuron free medium. The EC50,24h of the inhibition of photosystem II electron transport by linuron was about 9–13 μg l−1 for most of the macrophytes tested. For S. acutus the EC50,72h for inhibition of photosystem II electron flow was about 17 μg l−1 for the free suspension, and 22 μg l−1 for cells encapsulated in alginate beads. In a long-term indoor microcosm experiment, the photosystem II electron flow of the macrophytes E. nuttallii, C. demersum and the alga Spirogyra sp. was determined during 4 weeks of chronic exposure to linuron. The EC50,4weeks for the long-term exposure was 8.3, 8.7 and 25.1 μg l−1 for E. nuttallii, C. demersum and Spirogyra, respectively. These results are very similar to those calculated for the acute effects. The relative biomass increase of E. nuttallii in the microcosms was determined during 3 weeks of chronic exposure and was related to the efficiency of photosystem II electron transport as assessed in the different treatments. It is concluded that effects of the photosynthesis inhibiting herbicide on aquatic macrophytes, algae and algae encapsulated in alginate beads can be conveniently evaluated by measuring photosystem II electron transport by means of chlorophyll fluorescence. This method can be used as a rapid and non-destructive technique in aquatic ecological research. This revised version was published online in August 2006 with corrections to the Cover Date.     

Experimental immunological effectiveness and safety of pyoimmunogen vaccine against Pseudomonas aeruginosa infection

Pyoimmunogen, a polycomponent vaccine against P. aeruginosa infection, has been obtained in laboratory and semi-industrial conditions. The microbial biomass obtained from the strains belonging to O-serotypes (immunotypes) most frequently occurring in clinical practice has been used for producing protective antigens. The preparations have been found to contain proteins (peptides) and carbohydrates in the ratio 6 : 1 to 8 : 1, as well as traces of 2-keto-3-desoxyoctanate, which is indicative of the low content of endotoxin. The immunogenicity of the preparations has been studied experimentally by the active immunization of mice. In these experiments the animals vaccinated in a single injection were found to be protected from challenge with both homologous and heterologous P. aeruginosa strains. The high level of protection from infection caused by toxigenic strain PA-103 was registered. The preparations have low toxicity: LD50 for mice exceeds 2 mg (in protein content): after the multiple administration (7-10 times) of the preparation to mice and rats the weight of the experimental animals was not significantly different from the weight of the control animals.