Francisella tularensis blue-gray phase variation involves structural modifications of lipopolysaccharide o-antigen, core and lipid a and affects intramacrophage survival and vaccine efficacy

Francisella tularensis is a CDC Category A biological agent and a potential bioterrorist threat. There is no licensed vaccine against tularemia in the United States. A long-standing issue with potential Francisella vaccines is strain phase variation to a gray form that lacks protective capability in animal models. Comparisons of the parental strain (LVS) and a gray variant (LVSG) have identified lipopolysaccharide (LPS) alterations as a primary change. The LPS of the F. tularensis variant strain gains reactivity to F. novicida anti-LPS antibodies, suggesting structural alterations to the O-antigen. However, biochemical and structural analysis of the F. tularensis LVSG and LVS LPS demonstrated that LVSG has less O-antigen but no major O-antigen structural alterations. Additionally, LVSG possesses structural differences in both the core and lipid A regions, the latter being decreased galactosamine modification. Recent work has identified two genes important in adding galactosamine (flmF2 and flmK) to the lipid A. Quantitative real-time PCR showed reduced transcripts of both of these genes in the gray variant when compared to LVS. Loss of flmF2 or flmK caused less frequent phase conversion but did not alter intramacrophage survival or colony morphology. The LVSG strain demonstrated an intramacrophage survival defect in human and rat but not mouse macrophages. Consistent with this result, the LVSG variant demonstrated little change in LD₅₀ in the mouse model of infection. Furthermore, the LVSG strain lacks the protective capacity of F. tularensis LVS against virulent Type A challenge. These data suggest that the LPS of the F. tularensis LVSG phase variant is dramatically altered. Understanding the mechanism of blue to gray phase variation may lead to a way to inhibit this variation, thus making future F. tularensis vaccines more stable and efficacious.

Chemical composition of lipopolysaccharides isolated from various endophytic nitrogen-fixing bacteria of the genus Herbaspirillum

Bacteria from the genus Herbaspirillum are endophytes responsible for nitrogen fixation in gramineous plants of economic importance such as maize, sugarcane, sorghum, rice, and wheat. Some species are known to produce plant growth substances. In contrast, Herbaspirillum rubrisubalbicans strains are known to be mild plant pathogens. The molecular communication between the plant and the microbes might involve lipopolysaccharides present in the outer membrane of these gram-negative bacteria. Phenol-water extraction was used to obtain lipopolysaccharides from 7 strains of Herbaspirillum seropedicae (SmR1, Z67, Z78, ZA95, and M2) and H. rubrisubalbicans (M1 and M4). The electrophoretic profiles and chemical composition of the lipopolysaccharides obtained in the phenol and aqueous extracts were shown herein.

Identification of a novel ABC transporter required for desiccation tolerance, and biofilm formation in Rhizobium leguminosarum bv. viciae 3841

Rhizobium leguminosarum is a soil bacterium with the ability to form nitrogen-fixing nodules on the roots of leguminous plants. Soil-dwelling, free-living R. leguminosarum often encounters desiccation stress, which impacts its survival within the soil. The mechanisms by which soil bacteria resist the effects of desiccation stress have been described. However, the role of the cell envelope in the desiccation tolerance mechanisms of rhizobia is relatively uncharacterized. Using a transposon mutagenesis approach, a mutant of R. leguminosarum bv. viciae was isolated that was highly sensitive to desiccation. The mutation is located in the ATP-binding protein of an uncharacterized ATP-binding cassette transporter operon (RL2975-RL2977). Exopolysaccharide accumulation was significantly lower in the mutant and the decrease in desiccation tolerance was attributed to the decreased accumulation of exopolysaccharide. In addition to desiccation sensitivity, the mutant was severely impaired in biofilm formation, an important adaptation used by soil bacteria for survival. This work has identified a novel transporter required for physiological traits that are important for the survival of R. leguminosarum in the rhizosphere environment.

Rhizobium leguminosarum biovar viciae 3841, deficient in 27-hydroxyoctacosanoate-modified lipopolysaccharide, is impaired in desiccation tolerance, biofilm formation and motility

The lipopolysaccharide (LPS) of the Gram-negative legume symbiont Rhizobium leguminosarum biovar viciae 3,841 contains several unique modifications, including the addition of a 27-hydroxyoctacosanoic acid (27OHC28 : 0), also termed the very long chain fatty acid (VLCFA), attached at the 2' position of lipid A. A transposon mutant that lacks expression of two putative 3-oxo-acyl [acyl-carrier protein] synthase II genes, fabF1 and fabF2, from the VLCFA biosynthetic cluster, was isolated and characterized. MS indicated that the lipid A of the mutant lacked the VLCFA modification, and sodium deoxycholate (DOC)-PAGE of the LPS indicated further structural alterations. The mutant was characteristically sensitive to several stresses that would be experienced in the soil environment, such as desiccation and osmotic stresses. An increase in the excretion of neutral surface polysaccharides was observed in the mutant. This mutant was also altered in its attachment to solid surfaces, and was non-motile, with most of the mutant cells lacking flagella. Despite the pleiotropic effects of the mutation, these mutants were still able to nodulate legumes and fix atmospheric nitrogen. This report emphasizes that a structurally intact VLCFA-containing lipid A is critical to cellular traits that are important for survival in the rhizosphere.

Identification of two late acyltransferase genes responsible for lipid A biosynthesis in Moraxella catarrhalis

Lipid A is a biological component of the lipo-oligosaccharide of a human pathogen, Moraxella catarrhalis. No other acyltransferases except for UDP-GlcNAc acyltransferase, responsible for lipid A biosynthesis in M. catarrhalis, have been identified. By bioinformatics, two late acyltransferase genes, lpxX and lpxL, responsible for lipid A biosynthesis were identified, and knockout mutants of each gene in M. catarrhalis strain O35E were constructed and named O35ElpxX and O35ElpxL. Structural analysis of lipid A from the parental strain and derived mutants showed that O35ElpxX lacked two decanoic acids (C10:0), whereas O35ElpxL lacked one dodecanoic (lauric) acid (C12:0), suggesting that lpxX encoded decanoyl transferase and lpxL encoded dodecanoyl transferase. Phenotypic analysis revealed that both mutants were similar to the parental strain in their toxicity in vitro. However, O35ElpxX was sensitive to the bactericidal activity of normal human serum and hydrophobic reagents. It had a reduced growth rate in broth and an accelerated bacterial clearance at 3 h (P < 0.01) or 6 h (P < 0.05) after an aerosol challenge in a murine model of bacterial pulmonary clearance. O35ElpxL presented similar patterns to those of the parental strain, except that it was slightly sensitive to the hydrophobic reagents. These results indicate that these two genes, particularly lpxX, encoding late acyltransferases responsible for incorporation of the acyloxyacyl-linked secondary acyl chains into lipid A, are important for the biological activities of M. catarrhalis.

Role of different moieties from the lipooligosaccharide molecule in biological activities of the Moraxella catarrhalis outer membrane

Lipooligosaccharide (LOS), a major component of the outer membrane of Moraxella catarrhalis, consists of two major moieties: a lipid A and a core oligosaccharide (OS). The core OS can be dissected into a linker and three OS chains. To gain an insight into the biological activities of the LOS molecules of M. catarrhalis, we used a random transposon mutagenesis approach with an LOS specific monoclonal antibody to construct a serotype A O35Elgt3 LOS mutant. MALDI-TOF-MS of de-O-acylated LOS from the mutant and glycosyl composition, linkage, and NMR analysis of its OS indicated that the LOS contained a truncated core OS and consisted of a Glc-Kdo(2) (linker)-lipid A structure. Phenotypic analysis revealed that the mutant was similar to the wild-type strain in its growth rate, toxicity and susceptibility to hydrophobic reagents. However, the mutant was sensitive to bactericidal activity of normal human serum and had a reduced adherence to human epithelial cells. These data, combined with our previous data obtained from mutants which contained only lipid A or lacked LOS, suggest that the complete OS chain moiety of the LOS is important for serum resistance and adherence to epithelial cells, whereas the linker moiety is critical for maintenance of the outer membrane integrity and stability to preserve normal cell growth. Both the lipid A and linker moieties contribute to the LOS toxicity.

Biological and electrochemical treatment of used metalworking fluids: a toxicity-reduction evaluation

The aim of this study was to evaluate and compare the toxicity of spent metalworking fluids (MWFs) and two different effluents obtained by biologic and electrochemical treatment of spent MWFs toward aquatic organisms of different trophic levels. The obtained toxicity data was used to calculate safe concentrations of both effluents. The spent MWFs without treatment showed the highest toxicity among the tested samples and should be classified as "extremely toxic" (toward invertebrates) or "very toxic" (toward other test organisms). Both methods applied for MWFs treatment resulted in a significant decrease in toxicity of the treated MWFs, but the obtained effluents had still to be regarded as "toxic". The ranges of the values of acute toxic units for both effluents were significantly narrower than for the untreated spent MWFs. The values of the safe concentrations of the spent MWFs, the biologic effluent, and the water phase resulting from electrochemical emulsion breaking were equal to 0.013%, l.8%, and 1.3%, respectively, corresponding to chemical oxygen demand concentrations of 1.8%, 32, and 34 mg O(2)*L(-1). These values are far lower than the discharging limit of 125 mg O(2)*L(-1) for industrial effluents, according to the relevant Polish regulations. It is therefore recommended to include toxicity bioassay parameters into guidelines for wastewater discharges to surface waters because the existing chemical and physical parameters are not sufficient to describe the environmental impact of industrial wastewater. Toxicity bioassays can be a promising tool for evaluating the efficacy of unit operations in industrial wastewater treatment (toxicity reduction evaluation) as well as identification of toxic substances in effluents (toxicity identification evaluation).

[Evaluation of intrauterine insemination after two different methods of sperm preparation in cases of oligospermia in stimulated cycles]

Intrauterine insemination (IUI) is a widely accepted method of infertility treatment in case of oligospermia. Sperm requires special preparation to avoid applying of active ingredients and abnormal cells to uterine cavity. In this paper authors compared the efficiency of IUI after swim-up sperm preparation on Menezo B2 medium, with IxaPrep technic sperm preparation. In our material there were no significant differences in received results in relation to sperm preparation method.

[Neuropsychological evaluation of the results of treatment of hydrocephalus using a ventriculo-atrial valve]

In 25 patients with hydrocephalus of various grades and aetiology treated by insertion of ventriculoatrial valves neuropsychological investigations were carried out before and after this operation using the method of Luria and certain psychometric tests. The obtained results made possible isolation of three grades of impairment of higher nervous functions: III--afunction--10 patients, II--dysfunction--12 patients, I--eufunction--3 patients. Control neuropsychological examination two weeks after the operation demonstrated improvement of higher nervous functions in 6 cases with grade III and 11 patients with grade II impairment. In these cases radiological investigations demonstrated evidence of normotensive and hypertensive hydrocephalus and this was confirmed by measurements of intraventricular pressure of the cerebrospinal fluid. In 5 cases with grades III and II of damage no improvement was found. Radiograms and measurements of intraventricular pressure suggested in these cases hydrocephalus due to brain atrophy.

[Results of surgical treatment of aneurysms of the middle cerebral artery]

The authors present a group of 38 patients with middle cerebral artery aneurysms in whom 48 aneurysms were excluded from the cerebral circulation by microsurgical techniques. In 11 cases multiple aneurysms were found. In 2 cases the wall of the aneurysm was strengthened. In the light of this material and a survey of the pertinent literature the authors analyse the relationship between the results of surgical treatment and various factors. A significant increase in postoperative mortality was found with more severe condition of the patients by the Botterell scale. The factors worsening the prognosis were also: presence of intracerebral haematoma and aneurysm location in the bifurcation of an artery. Arteriospasm increased the incidence of neurological deficits.

[Nocturnal sleep patterns during treatment of hydrocephalus]

By polygraphic methods the authors studied the sleep patterns during treatment of patients with subtentorial tumours causing hydrocephalus. Sleep recording was carried out in three stages of treatment: 1) before insertion of ventriculo-atrial valve, (7 investigations), 2) on the 7th day after valve insertion (7 investigations), 3) two months after removal of the posterior fossa tumour (3 investigations). The control group included patients with peripheral nerve injury in whom sleep recording was done before and after surgical treatment. In cases with hydrocephalus and raised CSF pressure before valve insertion the cyclic pattern of sleep was disintegrated, showing long periods of light sleep (phase 1 + 2) interrupted by long periods of alertness, during sleep, mostly with elimination of the remaining sleep components. The decrease of CSF pressure after valve implantation was parallelled by partial normalization of sleep pattern, that is shortening of the light sleep phase and reduction of the number of alertness during sleeping hours, as well as prolongation of the phases of deep sleep and appearance of paradoxical sleep. However, only removal of the tumour from the posterior fossa made possible approximation of sleep elements to those in the control group. Sleep disintegration of varying intensity in patients with hydrocephalus may be reversible, the rate of normalization of sleep depends on the intensity of sleep disturbances in the initial stage of the disease, but return to nearly normal sleep is possible only after removal of the subtentorial tumour.

[Clinico-theoretical aspects of cerebrospinal fluid pressure changes associated with sleep analysis in patients with hydrocephalus caused by posterior fossa tumors]

In 6 patients treated for hydrocephalus caused by posterior fossa tumours simultaneous continuous measurement of intraventricular cerebrospinal fluid pressure and all-night polygraphic sleep recording were carried out before and after implantation of ventriculoatrial valve. It was observed that in patients with hydrocephalus and raised CSF pressure electrography demonstrated a breakdown of the cyclic sleep pattern with increased duration of light sleep and higher number of awakening episodes, and with reduced amount of deep sleep and nearly complete absence of REM sleep. The degree of sleep disturbances seemed to be correlated with increased value of CSF pressure. In that period discrepancies were observed between the sleep record suggesting waking and the behaviour of the patient who was asleep at that time. With normalization of CSF pressure record (after valve implantation) an improvement of sleep pattern was observed which approached the normal one.

[Studies on the cerebrospinal fluid pressure changes in patients treated for hydrocephalus by the so-called ventricular filling test. Preliminary report]

The curves of cerebrospinal fluid pressure (CFP) in the lateral cerebral ventricle during the so called ventricular filling-up test are presented in 6 patients with high-pressure and medium-pressure hydrocephalus as compared with CFP curves obtained in 2 patients with low-pressure hydrocephalus. The method of filling-up test (infusion test) is described. In this method portions of normal saline 2 ml each are administered rapidly into a lateral ventricle every 30 seconds. The obtained results demonstrated a difference in the shape of the CFP curves in patients with low-pressure open hydrocephalus as compared with patients with closed hydrocephalus. This could help in qualifying patients with hydrocephalus for treatment with ventriculo-atrial shunt.

[Surgical treatment of aneurysms of the anterior communicating artery using Yasargil's approach]

The results of surgical treatment in 19 cases of aneurysms of the anterior communicating artery from the approach described by Yasargil are described. In 16 patients the pedicle of the aneurysm was closed with a clip, in 2 cases the anterior communicating artery was excluded from the circulation by trapping, and in only 1 patient the aneurysm was enclosed in muscle and gazue. Control angiography demonstrated in 16 cases exclusion of the aneurysm from the circulation with maintenance of the patency of the main vessels, and in one case the sac of the aneurysm was partly shadowed. Good results were obtained in 80% of cases. One patient died (5%). Complications with development of Korsakoff's syndrome were observed in 3 patients (15%). The advantages of the approach described by Yasargil for the exposure and safe management of anterior communicating artery aneurysms are stressed.

[Changes in cerebrospinal fluid pressure in patients with hydrocephalus of various intensities]

In 12 patients with hydrocephalus caused by posterior fossa tumours continuous measurements of intraventricular CSFP were done before and after implantation of ventriculoatrial valve and after tumour removal. A fall of the mean CSFP from 31.57 mm Hg to 15.32 mm Hg was observed after valve implantation, and a further fall of the mean CSFP to 10.55 mm Hg after removal of the tumour. After valve implantation pathological A and B waves disappeared. Absence of improvement after different stages of treatment indicated poor functioning of the valve, but it was observed also in patients with inoperable tumours.

[Lumbosacral tumors of the vertebral canal simulating prolapse of the nucleus pulposus]

The authors analyzed the signs and clinical data from the preoperative period in 39 patients with tumours of the conus terminalis and cauda equina. Most patients had been treated for a long time for lumbar discopathy with sciatic pains. Most symptoms and neurological signs were in many cases suggestive rather of lumbar disc prolapse than spinal tumour. Radiological examinations of the spine failed in a overwhelming majority of cases to provide clues for correct diagnosis, only the type of tendon jerks loss, results of Queckenstedt's test and protein level in the cerebrospinal fluid suggested spinal tumor as a cause of the disease. Contract radiological examination of the vertebral canal gave definite answer in all cases.

[Aneurysm of pericallosal artery]

The authors describe 3 cases of saccular aneurysms of the pericallosal artery. They accounted for 3.36% of all intracranial aneurysms in the material of the authors. Difficulties in management of pericallosal artery aneurysms are discussed. All patients with aneurysms in this area were operated upon from an approach through the interhemispheric fissure and the results were good.