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The paper deals with the numerical simulation of strain localization in granular two-phase material. A gradient enhancement of modified Cam-clay model is introduced to overcome the problem of spurious discretization sensitivity of finite element solution. Two- and three-field finite elements implemented in the finite element analysis program (FEAP) are used in numerical simulations. The attention is focused on imperfection sensitivity of shear banding simulations. An application of the modelling framework to the slope stability problem is also included. [ABSTRACT FROM AUTHOR]

In Saccharomyces cerevixiae, which uses the nonlinear pathway of arginine biosynthesis, the first two enzymes, N-acetylglutamate synthase (NAGS) and N-acetylglutamate kinase (NAGK), are controlled by feedback inhibition. We have previously shown that NAGS and NAGK associate in a complex, essential to synthase activity and protein level [Abadjieva, A., Pauwels, K., Hilven, P. & Crabeel, M. (2001) J. Biol. Chem. 276, 42869-42880]. The NAGKs of ascomycetes possess, in addition to the catalytic domain that is shared by all other NAGKs and whose structure has been determined, a C-terminal domain of unknown function and structure. Exploring the role of these two domains in the synthase/kinase interaction, we demonstrate that the ascomycete-specific domain is required to maintain synthase activity and protein level. Previous results had suggested a participation of the third enzyme of the pathway, N-acetylglutamylphosphate reductase, in the metabolon. Here, genetic analyses conducted in yeast at physiological level, or in a heterologous background, dearly demonstrate that the reductase is dispensable for synthase activity and protein level. Most importantly, we show that the arginine feedback regulation of the NAGS and NAGK enzymes is mutually interdependent. First, the kinase becomes less sensitive to arginine feedback inhibition in the absence of the synthase. Second, and as in Neurospora craxsa, in a yeast kinase mutant resistant to arginine feedback inhibition, the synthase becomes feedback resistant concomitantly. We conclude that the NAGS/NAGK metabolon promotes the co-ordination of the catalytic activities and feedback regulation of the first two, flux controlling, enzymes of the arginine pathway. [ABSTRACT FROM AUTHOR]

The range of hosts exploited by a parasite is determined by several factors, including host availability, infectivity and exploitability. Each of these can be the target of natural selection on both host and parasite, which will determine the local outcome of interactions, and potentially lead to coevolution. However, geographical variation in host use and specificity has rarely been investigated. Maculinea (= Phengaris) butterflies are brood parasites of Myrmica ants that are patchily distributed across the Palæarctic and have been studied extensively in Europe. Here, we review the published records of ant host use by the European Maculinea species, as well as providing new host ant records for more than 100 sites across Europe. This comprehensive survey demonstrates that while all but one of the Myrmica species found on Maculinea sites have been recorded as hosts, the most common is often disproportionately highly exploited. Host sharing and host switching are both relatively common, but there is evidence of specialization at many sites, which varies among Maculinea species. We show that most Maculinea display the features expected for coevolution to occur in a geographic mosaic, which has probably allowed these rare butterflies to persist in Europe. This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.

Objectives: The aim of the study was to evaluate condition of the periodontium in pregnant women with pathological progress of the pregnancy, clinically and to compare it to periodontium in pregnant women in good health., Design: Over the last years, the studies have described that periodontitis caused by dental plaque, could be the risk factor for preterm birth and low birth weight., Materials and Methods: This study was performed in 80 pregnant women, 40 with pathologic pregnancy and 40 with normal pregnancy in it. Periodontal Indexes were used to evaluate periodontium., Results: In the searching group gingivitis gravidarum haemorrhagica diffusa and hyperplastica generalisata were dominating. In the control group gingivitis gravidatum simplex and hyperplastica localisata were observed., Conclusions: More severe manifestation of gingivitis gravidarum was noticed in pregnant women with risk of preterm low birth. We did not prove correlation between amount of bacterial dental plaque in pregnant women and risk of preterm low birth weight.

The free-living amoebae are ubiquitous organisms. They are found in humid soil and all water reservoirs, i.e. fresh, sea, freezing and hot water. They mainly feed on bacteria. Pathogenic properties of amoebae and the mechanisms underlying pathological changes induced during human infection have not yet been fully elucidated. They are the causative agents of primary amoebic meningo-encephalitis (PAM), granulomatous amebic encephalitis (GAE), a chronic progressive disease of the central nervous system, amebic keratitis (AK), a chronic eye infection; amebic pneumitis (AP), a chronic lung infection, and skin infection. Only a few isolates are strongly and permanently pathogenic to humans. Some isolates lose their pathogenic properties after one passage. It has been assumed that such "temporary", unstable pathogenic properties of the amoebae may be caused by internal factors carried by them. It is generally known that the free-living amoebae may be naturally infected with pathogenic bacteria, which have the ability to survive for a long time and to proliferate in the amoebae cells. The role of the amoeba in the process of maintaining, propagating and transmitting human pathogens has not been well recognized. It has been suggested that some infections can be acquired by inhaling aerosols containing amoebae cells filled with bacteria. The presence of bacteria inside the free-living amoebae possess a great challenge to organisations responsible for testing and inspecting the quality and cleanliness of surface waters, swimming pools and drinking water intakes.

To estimate vitamin A, E and C serum concentrations among forestry workers showing antibodies against Borrelia burgdorferi presence. Vitamins A, E and C concentrations were evaluated in 117 sera of forestry workers. 78 persons aged 18-63 (x=43.07) showed antibodies against Borrelia burgdorferi presence. In this group 13 persons showed presence of IgM, 42 persons with IgG and 23 with IgM and IgG. Control group consisted of 39 persons aged 18-56 years (x=40,97), with no detectable anti-Borrelia burgdorferi antibodies in serum. Serologic diagnosis was performed with use of ELISA kit - Borrelia recombinant IgM, IgG (Biomedica, Austria). Vitamins A and E serum concentrations were detected by RP-HPLC method with spectrophotometric detection (De Leenheet and co.). Vitamin C was detected by RP-HPLS method with spectrophotometric method (Ivanovic and co). Obtains results were statistically analysed. Significantly lower of vitamin A and E serum concentration of persons with anti-borrelia antibodies presence. The lowest concentration was observed in group showing presence of IgM and IgG. No significant difference in vitamin C serum concentration in examined groups was observed. These results may suggest that low serum concentrations of vitamin A and E may have influence on Borrelia burgdorferi infection development.

Aim: The purpose of the study was to evaluate parameters of oxidoreductive system in serum and cerebrospinal fluid (CSF) of patients with neuroborreliosis., Material and Methods: The cases were 25 patients aged 21 to 64 (x = 42.3) hospitalized with diagnosis of neuroborreliosis. Activity of superoxide dismutase (Cu, Zn-SOD), glutathione reductase (GSSG-R), glutathione peroxidase (GSH-Px) and concentration of sulphydryl groups (-SH) and malondialdehyde (MDA) in serum and CSF were tested. The control group consisted of 10 patients with diagnosis of discopathy. An examination was performed twice: before and after treatment., Results: Results of the study showed lack of stability in an oxidoreductive system during neuroborreliosis both in serum and in CSF. In CSF activity of SOD was increased while activity of GSH-Px and GSSG-R were decreased. Also concentration of -SH and lipid peroxidation products measured as MDA were increased. The increase of SOD, GSH-Px, GSSG-R activity and concentration of -SH and MDA in serum were detected., Conclusions: Disorders of an oxidoreductive system in CSF and serum during neuroborreliosis were observed. These changes persisted despite treatment and normalization of inflammatory CSF markers.