Die absolute Konfiguration der Hydroxy- und Epoxy-Iridale

Die Epoxy- und Hydroxyiridale sind eine Unterfamilie der mehr als vierzig bis heute bekannten Iridale, welche in Lipidextrakten von Schwertlilien gefunden wurden. Einige davon sind monocyclische Triterpene mit einer Homofarnesylseitenkette, die an unterschiedlichen Positionen hydroxyliert oder epoxidiert ist. Die Konfiguration des iridal-typischen Sechsringes ist durch Röntgenstrukturanalyse und chemischer Abbaureaktionen als 6R,10S,11S bestimmt worden. Eine Bestimmung der Stereozentren in der Seitenkette steht bisher noch aus. Die vorliegende Arbeit zeigt den Einsatz von NMR-spektroskopischen Untersuchungen und der CD Spektroskopie für die Bestimmung der absoluten Konfiguration der acyclischen Asymmetriezentren dieser Naturstoffe. Zum einem wurden diastereomere Ester der Naturstoffe hergestellt, deren Protonenresonanzverschiebungen, eine Aussage über die Stereochemie ermöglichen. Die Chiralität sekundärer allylischer Alkohole kann zudem mit der "exciton chirality"-Methode ermittelt werden. Dazu werden die Substanzen mit einem Reagenz, welches einen Chromophor besitzt, umgesetzt. Das CD-Spektrum der resultierenden Derivate zeigt dann einen Cotton-Effekt, dessen Vorzeichen in direktem Zusammenhang mit der absoluten Konfiguration des Alkohols steht. Für alle sekundären Alkohole wurde die R-Konfiguration ermittelt. Des Weiteren gelang die Umlagerung und Derivatisierung eines Epoxyiridals, dessen Konfiguration mit R interpretiert wurde. Die Verlässlichkeit und Gültigkeit des Verfahrens wurde an geeigneten Modellverbindungen mit bekannter absoluter Konfiguration demonstriert. Die untersuchten Iridale wurden aus entsprechenden Iris-Spezies isoliert. Bei der Auftrennung der pflanzlichen Extrakte konnten fünf neue Naturstoffe der Iridalfamilie isoliert und ihre Struktur aufgeklärt werden

Public health significance of chickenpox on ships - conclusions drawn from a case series in the port of Hamburg

Background: Despite international notification requirements, the magnitude of disease transmission on board ships remains undetermined. This case series aims to exemplify that varicella aboard ships is a topic of interest for maritime medicine and of public health significance. Material and methods: Systematic presentation of cases of chickenpox reported to the Hamburg Port Health Authority between November 2007 and April 2008. A systematic literature search on 'ships and chickenpox' was performed. Results: Five crew cases of chickenpox were reported from two passenger ships and two cargo ships. The cases originated from Indonesia (2), the Philippines (1), and Sri Lanka (2). Three cases were notified by the shipmaster, one by a general practitioner, and one by the immigration service. Sources of infection were other crewmembers, passengers, and persons in the home countries. Conclusions: This description of five varicella cases aboard ships points to the significance of the disease among seafarers. Many seafarers originate from tropical countries where seroconversion to varicella zoster virus generally occurs in late adolescents and adults. Thus, a substantial portion of the crew may be non-immune and have the potential to introduce the disease from their home country to the ship, or are at risk for infection on the ship. Port health authorities, shipmasters, and doctors need to be well informed about the relevance of chickenpox on ships and the recommended control measures. Travellers should be advised to report to the ship doctor with any signs of infectious disease. Int Marit Health 2010; 61, 1: 28-3

Endophytes Are Hidden Producers of Maytansine in Putterlickia Roots

Several recent studies have lent evidence to the fact that certain so-called plant metabolites are actually biosynthesized by associated microorganisms. In this work, we show that the original source organism(s) responsible for the biosynthesis of the important anticancer and cytotoxic compound maytansine is the endophytic bacterial community harbored specifically within the roots of Putterlickia verrucosa and P. retrospinosa plants. Evaluation of the root endophytic community by chemical characterization of their fermentation products using HPLC-HRMSn, along with a selective microbiological assay using the maytansine-sensitive type strain Hamigera avellanea revealed the endophytic production of maytansine. This was further confirmed by the presence of AHBA synthase genes in the root endophytic communities. Finally, MALDI-imaging-HRMS was used to demonstrate that maytansine produced by the endophytes is typically accumulated mainly in the root cortex of both plants. Our study, thus, reveals that maytansine is actually a biosynthetic product of root-associated endophytic microorganisms. The knowledge gained from this study provides fundamental insights on the biosynthesis of so-called plant metabolites by endophytes residing in distinct ecological niches

Laboratory-based surveillance of antimicrobial resistance in regions of Kenya:An assessment of capacities, practices, and barriers by means of multi-facility survey

BACKGROUND: Adequate laboratory capacity is critical in the implementation of coherent surveillance for antimicrobial resistance (AMR). We describe capacities and deficiencies in laboratory infrastructure and AMR surveillance practices among health facilities in Kenya to support progress toward broader sustainable laboratory-based AMR surveillance. METHODS: A convenience sample of health facilities from both public and private sectors across the country were selected. Information was obtained cross-sectionally between 5th October and 8th December 2020 through online surveys of laboratory managers. The assessment covered quality assurance, management and dissemination of AMR data, material and equipment, staffing, microbiology competency, biosafety and certification. A scoring scheme was developed for the evaluation and interpreted as (80% and above) facility is adequate (60–79%) requires some strengthening and (<60%) needing significant strengthening. Average scores were compared across facilities in public and private sectors, rural and urban settings, as well as national, county, and community levels. RESULTS: Among the participating facilities (n = 219), the majority (n = 135, 61.6%) did not offer bacterial culture testing, 47 (21.5%) offered culture services only and 37 (16.9%) performed antimicrobial susceptibility testing (AST). The major gaps identified among AST facilities were poor access to laboratory information management technology (LIMT) (score: 45.9%) and low uptake of external quality assessment (EQA) programs for cultures (score 67.7%). Access to laboratory technology was more than two-fold higher in facilities in urban (58.6%) relative to rural (25.0%) areas. Whilst laboratories that lacked culture services were found to have significant infrastructural gaps (average score 59.4%), facilities that performed cultures only (average score: 83.6%) and AST (average score: 82.9%) recorded significantly high scores that were very similar across areas assessed. Lack of equipment was identified as the leading challenge to the implementation of susceptibility testing among 46.8% of laboratories. CONCLUSIONS: We identified key gaps in laboratory information management technology, external quality assurance and material and equipment among the surveyed health facilities in Kenya. Our findings suggest that by investing in equipment, facilities performing cultures can be successfully upgraded to provide additional antimicrobial susceptibility testing, presenting a chance for a major leap toward improved AMR diagnostics and surveillance in the country

Comparative genomics revealed adaptive admixture in Cryptosporidium hominis in Africa

Cryptosporidiosis is a major cause of diarrhoeal illness among African children, and is associated with childhood mortality, malnutrition, cognitive development and growth retardation. Cryptosporidium hominis is the dominant pathogen in Africa, and genotyping at the glycoprotein 60 (gp60) gene has revealed a complex distribution of different subtypes across this continent. However, a comprehensive exploration of the metapopulation structure and evolution based on whole-genome data has yet to be performed. Here, we sequenced and analysed the genomes of 26 C. hominis isolates, representing different gp60 subtypes, collected at rural sites in Gabon, Ghana, Madagascar and Tanzania. Phylogenetic and cluster analyses based on single-nucleotide polymorphisms showed that isolates predominantly clustered by their country of origin, irrespective of their gp60 subtype. We found a significant isolation-by-distance signature that shows the importance of local transmission, but we also detected evidence of hybridization between isolates of different geographical regions. We identified 37 outlier genes with exceptionally high nucleotide diversity, and this group is significantly enriched for genes encoding extracellular proteins and signal peptides. Furthermore, these genes are found more often than expected in recombinant regions, and they show a distinct signature of positive or balancing selection. We conclude that: (1) the metapopulation structure of C. hominis can only be accurately captured by whole-genome analyses; (2) local anthroponotic transmission underpins the spread of this pathogen in Africa; (3) hybridization occurs between distinct geographical lineages; and (4) genetic introgression provides novel substrate for positive or balancing selection in genes involved in host–parasite coevolution

Analysis of aged sulfadiazine residues in soils using microwave extraction and liquid chromatagraphy tandem mass spectrometry

An efficient extraction of sulfadiazine residues from soils is difficult, as sulfadiazine is known to form quickly sequestering residues. The objective of this study was to optimize an exhaustive extraction for aged residues of sulfadiazine and its two major metabolites, N-acetylsulfadiazine and 4-hydroxysulfadiazine, from soil. For this purpose two representative used agricultural soils (Luvisol, Cambisol) were blended with manure derived from [(14)C]sulfadiazine-treated pigs and incubated at 10 degrees C in the laboratory. After different extraction tests with various solvent mixtures (two- to four-component mixtures with water, methanol, acetonitrile, acetone, and/or ethyl acetate), different pH values (pH 4 and 9), and extraction temperatures (up to 200 degrees C), soil extracts were measured by liquid scintillation counting and liquid chromatography coupled to tandem mass spectrometry. With respect to sulfadiazine yields, stability of soil extracts, and the amount of coextracted matrix, a microwave extraction of soil (15 min, 150 degrees C) using acetonitrile/water 1:4 (v/v) is the method of choice for the exhaustive extraction of aged sulfadiazine residues from soils