Distribution of Asian knotweeds on the Rhône River basin, France: A multi-scale model of invasibility that combines biophysical and anthropogenic factors.

Biotic and abiotic factors are important drivers of the introduction, dispersal and establishment of an invasive species in fluvial corridors. In this study, we propose to better understand the spatial distribution of Asian knotweeds and to model their invasibility at the river basin scale in the Rhône Mediterranean and Corsica regions, France. We implemented a multiscale analysis of biophysical and anthropogenic factors related to the presence of knotweeds. Subbasins were sampled (50-600 km2), a large dataset on knotweed occurrence and biotic/abiotic factors was collected, and logistic regression was applied. A robust logit model (accuracy: 90%; false positive rate: 13%) estimated the probability of the occurrence of knotweeds at the river basin scale. We found clear evidence of: i) spatial scale-dependent water availability for knotweed implantation (e.g., summer vs. winter rainfalls > 250 mm); ii) an important role of hydrogeomorphic forces in dispersal; and iii) interspecific competition in riparian areas. The occurrence of knotweeds is also closely related to human-derived pressures. The management of knotweeds on roads and railways in the vicinity of rivers may be a major source of propagules. Hydraulic infrastructures (dikes and mill weirs) may also have served as locations of knotweed introduction since the end of the nineteenth century and may play a major role in the propagule transfer of knotweed; to date, these infrastructures have provided favourable conditions for knotweed establishment. Despite local water authorities' increasing awareness of invasive plants, local management practices for flood mitigation, low awareness of roads/railway managers, and negative representations of knotweeds have probably largely contributed to their dispersion over decades. The final model intends to integrate these biophysical and human factors by providing an operational tool to help river managers determine the sensitivity of their river basins to knotweed invasion.

Management of dural arteriovenous fistulas - Helsinki and Kuopio experience.

Dural arteriovenous fistulas (DAVFs) are complex disorders, some of them with aggressive clinical behaviour. During past decades their treatment strategy has changed due to increased knowledge of their pathophysiology and natural history, and advances in treatment modalities. In asymptomatic cases or cases with mild symptoms in the absence of cortical venous drainage (CVD) no treatment is necessarily required, whereas aggressive DAVFs should be treated promptly by endovascular or microsurgical means.In our series of 323 patients with 333 fistulas, treated in two neurosurgical units in Finland since 1944, there were 265 true DAVFs and 68 Barrow type A caroticocavernous fistulas. Among the DAVFs there was a slight female predominance, 140 women (55%) and 115 men (45%), and the majority of the cases were located in the area of transverse and sigmoid sinuses. Mode of treatment in the early series was proximal ligation of feeding artery, and later craniotomy, endovascular treatment and radiosurgery, or combination of these treatments, with total occlusion rate being 53%.

[Lesions in the popliteal fossa with neurologic symptomatology--case reports, diagnostics and treatment]. / Léze podkolenní jamky s neurologickou symptomatologií--kazuistiky, diagnostika a lécba.

The lesions arising in the popliteal fossa are varied. We report two different lesions related to the peroneal nerve that presented with neurologic symptoms. Both were initially treated at surgical department with insufficient diagnostics and finally required a neurosurgical operation. We emphasize performing complete diagnostics that may avoid unnecessary burden for the patient and healthcare personnel. Patients with proven intimate relation of the lesion to nerve structures in the popliteal fossa should be referred to neurosurgical department.

The outcome, working ability and psychic changes after traumatic brain injury.

INTRODUCTION: Severe traumatic brain injury belongs to diagnoses with unfavourable outcome. Almost half of patients die due to this diagnose and many survivals remain severely disabled. MATERIAL AND METHODS: In our follow-up file we evaluated 52 patients treated at neurosurgical department due to this diagnosis. The survivals were subsequently examined in order to determine the severity of their objective neurological and cognitive problems. RESULTS: Mortality rate in our group reached 56 %. The overall results show cognitive disorders (memory disorders, prolonged latency and concentration disorders). Out of 92 % of surviving patients, it was neurological impairment that was most frequently (65 %) involved. CONCLUSION: Both cognitive disorders and neurological impairments are responsible for complicated resocialising including working ability which is very low after severe traumatic brain injury--in our group 26 %. Major obstacle can be seen in the psychological component of their over-all impaired quality of life (Tab. 5, Ref. 6).

The Met repressor-operator complex: DNA recognition by beta-strands.

The crystal structure of the E. coli met repressor in complex with a synthetic 19-base pair oligonucleotide reveals two dimeric repressor molecules bound to adjacent sites on the DNA. The oligonucleotide contains two adjacent repeats of an 8-mer known as a met-box, which represents the consensus of the met operator sites. Each met repressor dimer is centered on a met box and interacts with the adjacent dimer through antiparallel alpha-helices, which explained the observed cooperative nature of the binding. DNA binding takes place through the insertion of a beta-ribbon into the major groove of B-form DNA, representing a novel DNA binding motif. Sequence specificity arises from direct interactions between side chains of the beta-strands and the edges of the bases in the major groove. The local DNA conformation confers additional specificity through interactions between protein and the phosphate backbone. The repressor is activated through binding of S-adenosyl methionine (SAM), the corepressor, to the face opposite to that used for DNA binding. The lack of significant conformational change upon SAM binding, together with electrostatic calculations, suggests that DNA binding enhancement occurs through long-range electrostatic interactions.

Probing met repressor-operator recognition in solution.

The three-dimensional crystal structure of the Escherichia coli methionine repressor, MetJ, complexed with a DNA operator fragment is described in an accompanying article. The complex exhibits several novel features of DNA-protein interaction. DNA sequence recognition is achieved largely by hydrogen-bond contacts between the bases and amino-acid side chains located on a beta-ribbon, a mode of recognition previously hypothesized on the basis of modelling of idealized beta-strands and DNA, and mutagenesis of the Salmonella phage P22 repressors Arc and Mnt. The complex comprises a pair of MetJ repressor dimers which bind to adjacent met-box sites on the DNA, and contact each other by means of a pair of antiparallel alpha-helices. Here we assess the importance of these contacts, and also of contacts that would be made between the C-helices of the protein and DNA in a previous model of the complex, by studying mutations aimed at disrupting them. The role of the carboxy-terminal helix face in operator binding was unclear, but we demonstrate that recognition of operator sequences occurs through side chains in the beta-strand motif and that dimer-dimer interactions are required for effective repression.

Electron microscopic analysis of two nonconjugative derivatives of plasmid R1drd-19Km- from Escherichia coli.

The plasmids pON5300 and pON5304, nonconjugative variants of the plasmid R1drd-19Km, were analyzed by electron microscopy. It was found by heteroduplex mapping that a 1.4 kb DNA segment was inserted into EcoRI E fragment of both plasmids, where some tra-genes and oriT are localized. Although this DNA segment was mapped to the same region its orientation was different in each of the two plasmids. The inserted DNA segment was identified as an IS10R sequence on the basis of analysis of self-annealed molecules of pON5304 and their cleavage with EcoRV restriction enzyme. These methods enable us not only to map IS10R sequences on 87 kb pON5300 and 65 kb pON5304 molecules, respectively, but also to define their orientation.

Cloning of Candida boidinii DNA fragments promoting autonomous replication of plasmids in Saccharomyces cerevisiae.

Fragments of Candida boidinii chromosomal DNA were inserted into the integrative vector YIp-kanr and examined for the presence of sequences promoting autonomous replication of plasmids in Saccharomyces cerevisiae. Restriction maps of two plasmids, designated S6/4 and S6/5, originating from the same S. cerevisiae transformant, were constructed. Southern hybridization data confirmed that the plasmids carry sequences from the C. boidinii chromosome. Both plasmids transform S. cerevisiae strains at 4-5-fold higher frequency than cloning vectors based on the replication origin of the 2 microns plasmid. Mitotic stability of the constructed plasmids is similar to that of the 2 mu-based vector pNF2 in S. cerevisiae.

Plasmid pIMI38--the pBR322 derivative with increased stability in E. coli cells.

Plasmid pIM138 which had been characterized by the higher resistance of its DNA replication to the action of clorobiocin in comparison with the progenitor plasmid, was tested for its stability in host cells in the absence of the antibiotic. Growing without selective pressure, pIM138 was better maintained in cells than pBR322. The stability in the presence and in the absence of clorobiocin can be unanimously assigned to the plasmid itself, but some influence of host cells cannot be excluded.

Isolation and characterization of mutants of the RP4 plasmid coding for increased resistance to ampicillin.

E. coli strain J53(RP4) was mutagenized with ethyl methanesulfonate and N-methyl-N'-nitro-N-nitrosoguanidine. Clones showing a two-to threefold increase in resistance to ampicillin were produced. This increase was not due to an increased number of RP4 copies per chromosome. The level of penicillinase activity was twice higher in comparison with the parental strain. No detectable changes were found in the region coding for the resistance to ampicillin on the plasmid by restriction analysis.

The instability of plasmid pON5300 after its transformation into Escherichia coli K 12.

The plasmid R1drd-19 Km- and its derivative pON5300 were split by the PstI restriction enzyme; they differed in a 2.4 Mg/mol fragment which was present only in the pON5300. Both plasmids were present in 1-2 copies per chromosomal equivalent in E. coli JC5455 cells. The pON5300 is stable in its original mutagenized host but it segregates the enlarged region of the plasmid molecule after transformation into non-mutagenized E. coli JC5455. The possible explanation of this instability is discussed.

Stability of the hybrid plasmid pIM138 and its curing by some eliminating agents.

Hybrid plasmid pIM138 was constructed by insertion of a chromosomal fragment with the threonine operon from Escherichia coli into the pBR322 vector. Molar mass of pIM138 was 2.8 Mg/mol. Heteroduplexes between pBR322 vector and pIM138 hybrid DNA molecules were prepared. The hybrid plasmid shows a high stability against the curing effect of rifampicin and clorobiocin in E. coli SK1590 thr host.