Competence of urban rats as reservoir hosts for Lyme disease spirochetes

To determine whether urban rats serve efficiently as reservoir hosts for the agent of Lyme disease, we recorded the frequency of infection in nymphal Ixodes ricinus (L.) ticks that had fed as larvae on experimentally infected Norway rats, Rattus norvegicus (Berkenhout), or on black rats, R. rattus (L.), and evaluated the nidicolous venue of transmission. Subadult vector ticks attached readily to Norway rats as well as black rats and virtually all became infected in the course of feeding. Larval ticks detached when these nocturnally active hosts were at rest. Rats appeared to be competent reservoir hosts of Lyme disease spirochetes in a transmission cycle in urban sites.     

Work capacity evaluation within Social Security

Incapacity for work is not a medical but an economic concept. The difference between the earnings somebody could have had without health problems, and the possible earnings with health problems determine the degree of incapacity for work. Social security physicians and vocational experts together judge the degree of incapacity for work in discussion with the client. The physician judges the general possibilities of the client. The vocational expert selects possible jobs the client should be able to do. The disability allowances are relatively low. Treating physicians should take into account this and other negative aspects of incapacity for work.     

Activation of cutaneous dendritic cells by CpG-containing oligodeoxynucleotides: a role for dendritic cells in the augmentation of Th1 responses by immunostimulatory DNA

Genetic vaccination depends at least in part on the adjuvant properties of plasmids, properties that have been ascribed to unmethylated CpG dinucleotides in bacterial DNA. Because dendritic cells (DC) participate in the T cell priming that occurs during genetic vaccination, we reasoned that CpG-containing DNA might activate DC. Thus, we assessed the effects of CpG oligodeoxynucleotides (CpG ODN) on Langerhans cell (LC)-like murine fetal skin-derived DC (FSDDC) in vitro and on LC in vivo. Treatment with CpG ODN as well as LPS induced FSDDC maturation, manifested by decreased E-cadherin-mediated adhesion, up-regulation of MHC class II and costimulator molecule expression, and acquisition of enhanced accessory cell activity. In contrast to LPS, CpG ODN stimulated FSDDC to produce large amounts of IL-12 but only small amounts of IL-6 and TNF-alpha. Injection of CpG ODN into murine dermis also led to enhanced expression of MHC class II and CD86 Ag by LC in overlying epidermis and intracytoplasmic IL-12 accumulation in a subpopulation of activated LC. We conclude that immunostimulatory CpG ODN stimulate DC in vitro and in vivo. Bacterial DNA-based vaccines may preferentially elicit Th1-predominant immune responses because they activate and mobilize DC and induce them to produce large amounts of IL-12.     

Serum mitogenic activity on in vitro glial cells in Neurofibromatosis type 1

Under starvation conditions, a variety of stationary phase genes are up-regulated under the control of the stationary phase sigma factor RpoS including at least two peroxidases and a protective DNA binding protein Dps. Previous work suggested that the reversion to prototrophy of certain amino acid auxotrophs of Escherichia coli that occurs when the bacteria are starved of a required amino acid results from the accumulation of oxidative damage to guanine residues in DNA. We report here that three strains lacking RpoS are indistinguishable from wild type in their ability to undergo this starvation-associated mutation, suggesting that basal levels of catalase activity are more than adequate in these strains, and that the induction of catalases and other proteins controlled by rpoS does not contribute to the protection of the DNA, at least in cells starved in early stationary phase. In comparison, the introduction of a plasmid specifying the production of singlet oxygen scavengers (carotenoids) in stationary phase cells led to a roughly twofold reduction in mutant yield. The results suggest that singlet oxygen may be an important endogenously produced mutagen in resting cells.     

Supplantation of mental operations on graphs

Research findings show the difficulties younger students have in working with graphs. Higher mental operations are necessary for a skilled interpretation of abstract representations. We suggest connecting a concrete representation of the modeled problem with the related graph. The idea is to illustrate essential mental operations externally. This is called supplantation. We provide this special kind of support in a multimedia learning environment using several computer-specific features. Based on an information-processing model we identify two different types of supplantation of mental operations on graphs: first, supplantation of how to relate a certain point of the graph to the underlying concrete object or situation. Second, supplantation of how a point of the graph and the underlying fact or situation co-vary. In an empirical study, combinations of these types were investigated. The results indicate that such a supplantation of mental operations on graphs can become a useful tool to support adequate understanding of graphs. However, supplantation should be adjusted to individual abilities.     

Photoregulation of cot-1, a kinase-encoding gene involved in hyphal growth in Neurospora crassa

Lattice-like perineuronal accumulations of extracellular-matrix proteoglycans have been shown to develop during postnatal maturation and to persist throughout life as perineuronal nets (PNs) in many brain regions. However, the dynamics of their reorganization in adults are as yet unknown. The aim of the present study was to examine the capability of PNs for reconstitution after experimental destruction and to search for possible consequences of extracellular-matrix degradation for neurons and glial cells. The changes were induced by single intracortical injections of Proteus vulgaris chondroitinase ABC and studied after postinjection periods of 1 day to 5 months. The N-acetylgalactosamine-binding Wisteria floribunda agglutinin (WFA), an antibody against chondroitin-sulphate proteoglycans, three antibodies recognizing initial chondroitin or chondroitin-sulphate moieties ('stubs') of proteoglycan core proteins, an antibody against the hyaluronan-binding protein component of versican, and biotinylated hyaluronectin, which binds to hyaluronan, were used as cytochemical markers. One day postinjection, the WFA-binding sites and hyaluronan were shown to be almost completely removed within a circumscribed digestion zone. The staining of different core-protein components revealed only fragments of PNs. These changes were found to be partly compensated 4 weeks after injection of chondroitinase ABC. After 8 and 12 weeks postinjection, the cytochemical and structural characteristics as well as the area-specific distribution patterns of PNs were progressively reconstituted. At 5 months postinjection, they could not be distinguished from those in untreated tissue. In contrast to such transient changes, a diffuse chondroitin-sulphate proteoglycan immunoreactivity persisted in the neuropil. Loss of neurons or alterations of their structure as well as reactions of glial cells were not observed. We conclude from this study that PNs, enzymatically destroyed in the adult rat brain, can be completely reconstituted, but the restoration of their extracellular-matrix components needs several months.     

DNA sequencing and analysis of the low-Ca2+-response plasmid pCD1 of Yersinia pestis KIM5

The low-Ca2+-response (LCR) plasmid pCD1 of the plague agent Yersinia pestis KIM5 was sequenced and analyzed for its genetic structure. pCD1 (70,509 bp) has an IncFIIA-like replicon and a SopABC-like partition region. We have assigned 60 apparently intact open reading frames (ORFs) that are not contained within transposable elements. Of these, 47 are proven or possible members of the LCR, a major virulence property of human-pathogenic Yersinia spp., that had been identified previously in one or more of Y. pestis or the enteropathogenic yersiniae Yersinia enterocolitica and Yersinia pseudotuberculosis. Of these 47 LCR-related ORFs, 35 constitute a continuous LCR cluster. The other LCR-related ORFs are interspersed among three intact insertion sequence (IS) elements (IS100 and two new IS elements, IS1616 and IS1617) and numerous defective or partial transposable elements. Regional variations in percent GC content and among ORFs encoding effector proteins of the LCR are additional evidence of a complex history for this plasmid. Our analysis suggested the possible addition of a new Syc- and Yop-encoding operon to the LCR-related pCD1 genes and gave no support for the existence of YopL. YadA likely is not expressed, as was the case for Y. pestis EV76, and the gene for the lipoprotein YlpA found in Y. enterocolitica likely is a pseudogene in Y. pestis. The yopM gene is longer than previously thought (by a sequence encoding two leucine-rich repeats), the ORF upstream of ypkA-yopJ is discussed as a potential Syc gene, and a previously undescribed ORF downstream of yopE was identified as being potentially significant. Eight other ORFs not associated with IS elements were identified and deserve future investigation into their functions.