Tuning the redox properties of the titanocene(III)/(IV)-couple for atom-economical catalysis in single electron steps.

Radical-based transformations are an attractive target for the development of catalytic processes due to ease of radical generation, high functional group tolerance and selectivity of bond-forming reactions. In spite of these appealing features, the potential of radicals as key intermediates in catalysis remains largely untapped. Herein we present recent work that exploits the innate ability of titanocene-based catalysts to undergo both oxidative addition and reductive elimination in single electron steps. We further demonstrate that tuning the redox properties of the titanocene-based catalyst can be used to develop efficient catalytic free radical processes including tetrahydrofuran synthesis, and radical arylation.

[EurSafety Health-Net: MRSA Eradication in Nursing Homes and Home Care - A Practice Report]. / EurSafety Health-Net: MRSA-Sanierung in der Pflege (MSP) - ein Praxisbericht.

In 2009 the project EurSafety Health-Net, funded by Interreg IVa, was initiated in order to create a cross-border quality alliance to enhance patient safety in the field of infectious diseases. Within this framework, several studies and projects addressing key topics of infection control were carried out. We describe the two-year project "MRSA decolonisation in care settings (MSP)", which aimed at evaluating a simple and economic way of decolonisation of non-hospitalised MRSA carriers in 2 districts in Lower Saxony. In the course of the project 181 decolonisations of MRSA carriers were performed by nursing homes and nursing services for outpatients in cooperation with the local public health authorities of the districts Ammerland and Grafschaft Bentheim. Of 181 cases 134 were eligible for statistical analysis. The project provided protocols for 2 different starting situations: 1) Continuing and completing a decolonisation treatment subsequent to a hospital stay by nursing services for outpatients or in a nursing home. 2) Starting a decolonisation treatment in a nursing home or by nursing services for outpatients. The carriers were provided with the required materials either by the hospitals (situation 1) or by the local public health authorities (situation 2) free of charge. The decolonisation treatment and the testing were offered only to carriers free of properties deemed as decolonisation obstacles and was applied without involvement of the general practitioner. Short- and long-term success of the 5 day decolonisation treatment was tested afterwards by two swabs (14 days and 6 months after the end of the treatment). The results of the 6-month control swabs showed that 45% of the carriers were successfully decolonised in the long term. All parties involved regarded the procedure of the MSP project as effective with respect to the target. Thus, even after the project was finished, both districts continued applying the MSP protocol.

Screening for colorectal lesions with high-resolution video colonoscopes in a German male average-risk population at 40 to 59 years of age.

BACKGROUND: Prevalence data for colorectal neoplastic lesions obtained from screening colonoscopies have recently been reported for a U. S. American and a Polish average-risk population. However, prevalence data for a German average-risk population have not been published. METHODS: From 1998 until 2003 a screening colonoscopy was offered to all male participants of a health assessment program. In a total of 618 volunteers with an average risk for colorectal cancer, polypoid lesions were identified and removed using high-resolution video colonoscopes. The histological features of the lesions were categorised according to those of the most advanced one. An advanced lesion was defined as an adenoma of at least 1 cm in diameter, a polyp with villous histological features or high-grade intraepithelial neoplasms or a cancer. Data were analysed in two groups: age 40 - 49 years (group A) and age 50 - 59 years (group B). RESULTS: In group A (age 40 - 49 years, n = 285), 133 subjects (47 %) had polypoid lesions. Histological findings revealed that 57 subjects (20 %) had non-neoplastic and 76 subjects (27 %) had neoplastic lesions. In nine cases (3.2 %) polyps were classified as advanced lesions with a maximal diameter of 35 mm. In group B (age 50 - 59, n = 333), 183 subjects (55 %) had polypoid lesions. Histological findings revealed that 64 subjects (19 %) had non-neoplastic and 119 subjects (36 %) had neoplastic lesions. Among those, 34 (10.2 %) had advanced lesions with a maximal diameter of 55 mm. In neither group was an invasive cancer detected. The difference in the prevalence of neoplastic lesions between the two age groups was statistically significant (chi (2) = 5.85). An exceptionally high rate of 27 % neoplastic lesions was detected in subjects at 40 to 49 years of age. The rate of detected lesions in the group of older subjects was 36 %. CONCLUSION: By using high-resolution endoscopes we found an unexpectedly large number of neoplastic lesions in the colon even in a relatively young average-risk population. The question whether screening colonoscopy should therefore not only aim at detecting early colorectal cancer but also at identifying and removing precursor adenomas at younger ages clearly deserves further attention.

[Surveillance of viral hepatitis in Lower Saxony for investigating risk factors: results and experiences from a regional public health project 1999-2001]. / Virushepatitis-Surveillance in Niedersachsen zur Erhebung von Risikofaktoren: Ergebnisse und Erfahrungen aus einem OGD-Regionalprojekt 1999-2001.

In Lower Saxony, a regional public health project for an enlarged surveillance of viral hepatitis was carried out from 1999 to 2001. Five district public health authorities collected additional information on notified viral hepatitis cases in a standardised way, particularly regarding risk factors. In the survey, 270 hepatitis (hep.) cases were investigated, among them hep. A 51 (18.9%), hep. B 87 (32.2%) and hep. C 132 (48.9%). The proportion of chronic cases and healthy carriers was as follows: hep. A 0%, hep. B 47.1% and hep. C 79.5%. In approximately 50% of the cases of all three forms risk factors could be identified. The most frequent risk factors were in hep. A visits to foreign countries (29.4%), contacts to infected individuals (17.6%) and attendance at public institutions or care facilities (13.7%), in hep. B visits to foreign countries (24.1%), contacts to infected individuals (19.5%; sexual contacts 16.1%) and medical treatments (19.5%) and in hep. C injecting drug use (31.1%) and medical treatments (18.2%; 9.8% blood transfusion in the past in combination with chronic hep. C). The results are in accordance with current data under the new infection protection law, where reporting of chronic cases was mostly abolished. In the survey, the well-known risk factors were confirmed, but some risks were reported more frequently than in other surveys, e. g. sexual behaviour for hep. B or injecting drugs for hep. C.

[Environmental studies of asymptomatic kindergarten children as carriers of enterohemorrhagic Escherichia coli (EHEC) in the Ammerland district]. / Umgebungsuntersuchungen bei asymptomatischen Kindergartenkindern als Ausscheider von enterohämorrhagischen Escherichia coli (EHEC) im Landkreis Ammerland.

The increase of serious EHEC diseases in the northwest Lower Saxony in summer 1997 was accompanied by a lively discussion on the hazard represented by this pathogen which gained a large amount of media attention. The Lower Saxony Public Health Department initiated a study of this case in the Weser-Ems government district to investigate the spread of EHEC by children and their supervisors in kindergartens receiving certified raw milk supply. This established that there were ten kindergarten children in the Ammerland rural district who were asymptomatik EHEC carriers. The Local Public Health Department immediately carried out the necessary epidemic hygiene measures. First of all, control investigations were performed on the affected children, including environmental investigations on their families and contracts. The results of these investigations revealed the need to carry out additional environmental investigations in two kindegartens (follow-up investigations) as well as amongst employees in a hospital canteen. Within the families, a mother of an affected child was also identified as another asymptomatic EHEC carrier. However, the strains that were isolated reflected different serotypes. In total, the investigation of 337 people in contact with the eleven asymptomatic EHEC carriers did not confirm any person-to-person transmission--even though three of the kindergarten children shedding the organisms for 6-10 weeks attended the kindergartens for at least 4 weeks. No EHEC disease occurred in the communal facilities, neither were any positive cases identified by additional control investigations. The results indicate a probable lower rate of infectiousness by healthy EHEC carriers than was previously thought to be the case. Further studies are needed to decide if in future one should proceed on a case by case basis when considering the reauthorization of affected children and other people to enter communal facilities.

The identification of genes with unique and essential functions in the development of the zebrafish, Danio rerio.

In a large-scale screen, we isolated mutants displaying a specific visible phenotype in embryos or early larvae of the zebrafish, Danio rerio. Males were mutagenized with ethylnitrosourea (ENU) and F2 families of single pair matings between sibling F1 fish, heterozygous for a mutagenized genome, were raised. Egg lays were obtained from several crosses between F2 siblings, resulting in scoring of 3857 mutagenized genomes. F3 progeny were scored at the second, third and sixth day of development, using a stereomicroscope. In a subsequent screen, fixed embryos were analyzed for correct retinotectal projection. A total of 4264 mutants were identified. Two thirds of the mutants displaying rather general abnormalities were eventually discarded. We kept and characterized 1163 mutants. In complementation crosses performed between mutants with similar phenotypes, 894 mutants have been assigned to 372 genes. The average allele frequency is 2.4. We identified genes involved in early development, notochord, brain, spinal cord, somites, muscles, heart, circulation, blood, skin, fin, eye, otic vesicle, jaw and branchial arches, pigment pattern, pigment formation, gut, liver, motility and touch response. Our collection contains alleles of almost all previously described zebrafish mutants. From the allele frequencies and other considerations we estimate that the 372 genes defined by the mutants probably represent more than half of all genes that could have been discovered using the criteria of our screen. Here we give an overview of the spectrum of mutant phenotypes obtained, and discuss the limits and the potentials of a genetic saturation screen in the zebrafish.

Mutations affecting the formation of the notochord in the zebrafish, Danio rerio.

In a large scale screen for mutants with defects in the embryonic development of the zebrafish we identified mutations in four genes,floating head (flh), momo (mom), no tail (ntl), and doc, that are required for early notochord formation. Mutations in flh and ntl have been described previously, while mom and doc are newly identified genes. Mutant mom embryos lack a notochord in the trunk, and trunk somites from the right and left side of the embryo fuse underneath the neural tube. In this respect mom appears similar to flh. In contrast, notochord precursor cells are present in both ntl and doc embryos. In order to gain a greater understanding of the phenotypes, we have analysed the expression of several axial mesoderm markers in mutant embryos of all four genes. In flh and mom, Ntl expression is normal in the germ ring and tailbud, while the expression of Ntl and other notochord markers in the axial mesodermal region is disrupted. Ntl expression is normal in doc embryos until early somitic stages, when there is a reduction in expression which is first seen in anterior regions of the embryo. This suggests a function for doc in the maintenance of ntl expression. Other notochord markers such as twist, sonic hedgehog and axial are not expressed in the axial mesoderm of ntl embryos, their expression parallels the expression of ntl in the axial mesoderm of mutant doc, flh and mom embryos, indicating that ntl is required for the expression of these markers. The role of doc in the expression of the notochord markers appears indirect via ntl. Floor plate formation is disrupted in most regions in flh and mom mutant embryos but is present in mutant ntl and doc embryos. In mutant embryos with strong ntl alleles the band of cells expressing floor plate markers is broadened. A similar broadening is also observed in the axial mesoderm underlying the floor plate of ntl embryos, suggesting a direct involvement of the notochord precursor cells in floor plate induction. Mutations in all of these four genes result in embryos lacking a horizontal myoseptum and muscle pioneer cells, both of which are thought to be induced by the notochord. These somite defects can be traced back to an impairment of the specification of the adaxial cells during early stages of development. Transplantation of wild-type cells into mutant doc embryos reveals that wild-type notochord cells are sufficient to induce horizontal myoseptum formation in the flanking mutant tissue. Thus doc, like flh and ntl, acts cell autonomously in the notochord. In addition to the four mutants with defects in early notochord formation, we have isolated 84 mutants, defining at least 15 genes, with defects in later stages of notochord development. These are listed in an appendix to this study.

Mutations affecting the cardiovascular system and other internal organs in zebrafish.

In a screen for early developmental mutants of the zebrafish, we have identified mutations specifically affecting the internal organs. We identified 53 mutations affecting the cardiovascular system. Nine of them affect specific landmarks of heart morphogenesis. Mutations in four genes cause a failure in the fusion of the bilateral heart primordia, resulting in cardia bifida. In lonely atrium, no heart venticle is visible and the atrium is directly fused to the outflow tract. In the overlooped mutant, the relative position of the two heart chambers is distorted. The heart is enormously enlarged in the santa mutant. In two mutants, scotch tape and superglue, the cardiac jelly between the two layers of the heart is significantly reduced. We also identified a number of mutations affecting the function of the heart. The mutations affecting heart function can be subdivided into two groups, one affecting heart contraction and another affecting the rhythm of the heart beat. Among the contractility group of mutants are 5 with no heart beat at all and 15 with a reduced heart beat of one or both chambers. 6 mutations are in the rhythmicity group and specifically affect the beating pattern of the heart. Mutations in two genes, bypass and kurzschluss, cause specific defects in the circulatory system. In addition to the heart mutants, we identified 23 mutations affecting the integrity of the liver, the intestine or the kidney. In this report, we demonstrate that it is feasible to screen for genes specific for the patterning or function of certain internal organs in the zebrafish. The mutations presented here could serve as an entry point to the establishment of a genetic hierarchy underlying organogenesis.

Characterization of zebrafish mutants with defects in embryonic hematopoiesis.

As part of a large scale chemical mutagenesis screen of the zebrafish (Danio rerio) genome, we have identified 33 mutants with defects in hematopoiesis. Complementation analysis placed 32 of these mutants into 17 complementation groups. The allelism of the remaining 1 blood mutant is currently unresolved. We have categorized these blood mutants into four phenotypic classes based on analyses of whole embryos and isolated blood cells, as well as by in situ hybridization using the hematopoietic transcription factors GATA-1 and GATA-2. Embryos mutant for the gene moonshine have few if any proerythroblasts visible on the day circulation begins and normal erythroid cell differentiation is blocked as determined by staining for hemoglobin and GATA-1 expression. Mutations in five genes, chablis, frascati, merlot, retsina, thunderbird and two possibly unique mutations cause a progressive decrease in the number of blood cells during the first 5 days of development. Mutations in another seven genes, chardonnay, chianti, grenache, sauternes, weiflherbst and zinfandel, and two additional mutations result in hypochromic blood cells which also decrease in number as development proceeds. Several of these mutants have immature cells in the circulation, indicating a block in normal erythroid development. The mutation in zinfandel is dominant, and 2-day old heterozygous carriers fail to express detectable levels of hemoglobin and have decreasing numbers of circulating cells during the first 5 days of development. Mutations in two genes, freixenet and yquem, result in the animals that are photosensitive with autofluorescent blood, similar to that found in the human congenital porphyrias. The collection of mutants presented here represent several steps required for normal erythropoiesis. The analysis of these mutants provides a powerful approach towards defining the molecular mechanisms involved in vertebrate hematopoietic development.

Mutations affecting xanthophore pigmentation in the zebrafish, Danio rerio.

In a large-scale screen for mutants with defects in embryonic development we identified 17 genes (65 mutants) specifically required for the development of xanthophores. We provide evidence that these genes are required for three different aspects of xanthophore development. (1) Pigment cell formation and migration (pfeffer and salz); (2) pigment synthesis (edison, yobo, yocca and brie) and (3) pigment translocation (esrom, tilsit and tofu). The number of xanthophore cells that appear in the body is reduced in embryos with mutations in the two genes, salz and pfeffer. In heterozygous and homozygous salz and pfeffer adults, the melanophore stripes are interrupted, indicating that xanthophore cells have an important function in adult melanophore pattern formation. Most other genes affect only larval pigmentation. In embryos mutant for edison, yobo, yocca and brie, differences in pteridine synthesis can be observed under UV light and by thin-layer chromatography. Homozygous mutant females of yobo show a recessive maternal effect. Embryonic development is slowed down and embryos display head and tail truncations. Xanthophores in larvae mutant in the three genes esrom, tilsit and tofu appear less spread out. In addition, these mutants display a defect in retinotectal axon pathfinding. These mutations may affect xanthophore pigment distribution within the cells or xanthophore cell shape. Mutations in seven genes affecting xanthophore pigmentation remain unclassified.

Mutations affecting pigmentation and shape of the adult zebrafish.

Mutations causing a visible phenotype in the adult serve as valuable visible genetic markers in multicellular genetic model organisms such as Drosophila melanogaster, Caenorhabditis elegans and Arabidopsis thaliana. In a large scale screen for mutations affecting early development of the zebrafish, we identified a number of mutations that are homozygous viable or semiviable. Here we describe viable mutations which produce visible phenotypes in the adult fish. These predominantly affect the fins and pigmentation, but also the eyes and body length of the adult. A number of dominant mutations caused visible phenotypes in the adult fish. Mutations in three genes, long fin, another long fin and wanda affected fin formation in the adult. Four mutations were found to cause a dominant reduction of the overall body length in the adult. The adult pigment pattern was found to be changed by dominant mutations in wanda, asterix, obelix, leopard, salz and pfeffer. Among the recessive mutations producing visible phenotypes in the homozygous adult, a group of mutations that failed to produce melanin was assayed for tyrosinase activity. Mutations in sandy produced embryos that failed to express tyrosinase activity. These are potentially useful for using tyrosinase as a marker for the generation of transgenic lines of zebrafish.

The polarity of the dorsoventral axis in the Drosophila embryo is defined by an extracellular signal.

Twelve maternal effect loci are required for the production of Drosophila embryos with a correct dorsoventral axis. Analysis of mosaic females indicates that the expression of the genes nudel, pipe, and windbeutel is required in the somatic tissue, presumably in the follicle cells that surround the oocyte. Thus, information coming from outside the egg cell influences dorsoventral pattern formation during embryogenesis. In transplantation experiments, the perivitelline fluid from the compartment surrounding the embryo can restore dorsoventral pattern to embryos from females mutant for nudel, pipe, or windbeutel. The positioning of the transplanted pervitelline fluid also determines the polarity of the restored dorsoventral axis. We propose that the polarizing activity, normally present at the ventral side of the egg, is a ligand for the Toll receptor. Presumably, local activation of the Toll protein by the ligand initiates the formation of the nuclear concentration gradient of the dorsal protein, thereby determining dorsoventral pattern.