[Gut microbiome and anorexia nervosa : The relationship between microbiome and gut-brain interaction in the context of anorexia nervosa]. / Darmmikrobiom und Anorexia nervosa : Der Zusammenhang von Mikrobiom und Darm-Gehirn-Interaktion im Kontext der Anorexia nervosa.

In recent years the intestinal microbiome and its interaction with the brain has aroused a growing interest. The findings gained in the course of this research are of great relevance not only to basic scientists but also to clinicians, as studies suggest an association between an altered microbiome and various somatic (e.g. chronic inflammatory intestinal diseases, obesity and diabetes) as well as psychiatric diseases (e.g. anxiety disorders, depression). In addition to a direct influence of the microbiome on the brain and behavior, various mechanisms seem to be relevant, including altered energy intake from food, hormonal changes, probably increased intestinal permeability as well as inflammatory and immunological processes. Anorexia nervosa (AN) is the third most common chronic disease in adolescence and has the highest mortality rate among all mental disorders. In addition to extremely restrictive eating habits, weight loss and comorbid anxiety and depression symptoms, endocrine changes and an increased autoimmune and inflammatory response are characteristic. Since AN is particularly strongly linked to eating behavior and nutrition, research into the microbiome seems very promising, especially with respect to this disease. This article gives a first insight into the underlying processes that play a role in gut-brain interaction in the context of AN and summarizes the previous empirical findings on this topic. Finally, an outlook on future research and possible implications for the therapeutic practice and treatment of AN is given.

Interactive effects of extreme temperature and a widespread coastal metal contaminant reduce the fitness of a common tropical copepod across generations.

Tropical coastal areas are increasingly exposed to temperature extremes from marine heatwaves and contaminants from anthropogenic activities. The interactive effects of these environmental changes on marine life are understudied. We investigated the direct and cross-generational effects of copper (Cu) on F0 and F1 generations of the common tropical copepod Pseudodiaptomus annandalei under extreme temperatures (30 and 34 °C). In F0, Cu exposure reduced survival and nauplii production; these patterns were more pronounced at 34 °C and in females. F0 Copepods produced more faecal pellets at 34 °C than 30 °C, indicating a higher energetic demand. In F1, the number of F1 adults was lower in CuF0 and at 34 °C. Cu-exposed F0 produced larger adult F1, while exposure to 34 °C resulted in smaller adult F1. Our results show that tropical copepods are highly vulnerable to the interactive effects of contaminants and extreme temperatures.

Additive effects of cisplatin and radiation in human tumor cells under oxic conditions.

The interaction of cisplatin and irradiation was studied in vitro in four human cell lines. Additive effects were observed for the combination given either simultaneously or sequentially. No influence on recovery was seen in split-dose experiments. It is concluded that radiosensitization cannot be presumed in every clinical setting of combined treatment with radiation and cisplatin.

Mutagenic action of 5-nitroimidazoles: in vivo induction of GC-->CG transversion in two Bacteroides fragilis reporter genes.

The in vivo mutagenic potential of two 5-nitroimidazoles, metronidazole and dimetridazole, was evaluated in Bacteroides fragilis, a strictly anaerobic bacterium. Two antibiotic resistance genes, tetA(Q)3 and nimA, were used as DNA targets. The forward and back mutations were identified by nucleotide sequence analysis. Both drugs induced GC-->CG transversion exclusively. The results suggest that the reactive molecules generated during the intracellular reduction of the 5-nitroimidazoles are responsible for both base pair substitutions and DNA strand breaks, although the mechanisms and targets may be different.

Detection by PCR of the nim genes encoding 5-nitroimidazole resistance in Bacteroides spp.

A PCR method was developed for detection of the nim genes encoding 5-nitrolmidazole resistance in Bacteroides spp. Two PCR primers specific for nim genes were designed. They allowed amplification of a 458-bp fragment from all characterized plasmid- and chromosome-borne metronidazole resistance genes. The specificity of the method was tested with DNA from metronidazole-sensitive Bacteroides spp. strains and from other strains of unrelated species. Each DNA preparation was analyzed with and without an internal positive control to verify that the absence of PCR amplification product was not due to inhibition of the Taq polymerase inhibitors. By this technique, two newly discovered metronidazole-resistant clinical strains of Bacteroides fragilis were shown to harbor resistance genes undetectable by Southern blotting. In spite of the sequence divergence of the nim genes, the PCR method is thus suitable for epidemiological investigations. The amplification method also revealed that nim-related resistance genes were not present in either Streptomyces strain S6670, a natural producer of 2-nitroimidazole, or in Enterococcus faecalis strains, which have been suggested to possess metronidazole-inactivating enzyme.

Identification and DNA sequence of the mobilization region of the 5-nitroimidazole resistance plasmid pIP421 from Bacteroides fragilis.

The nucleotide sequence of the DNA mobilization region of the 5-nitroimidazole resistance plasmid pIP421, from strain BF-F239 of Bacteroides fragilis, was determined. It contains a putative origin of transfer (oriT) including three sets of inverted repeats and two sequences reminiscent of specific integration host factor binding sites. The product of the mobilization gene mob421 (42.2 kDa) is a member of the Bacteroides mobilization protein family, which includes the MobA of pBI143, NBUs, and Tn4555. Sequence similarity suggests that it has both oriT binding and nicking activities. The transfer frequency of pIP421 in a B. fragilis donor strain possessing a Tc(r) or Tc(r) Em(r)-like conjugative transposon was significantly enhanced by tetracycline. Moreover, the mobilization region of pIP421 confers the ability to be mobilized from Escherichia coli by an IncP plasmid.

Conjugal transfer of the 5-nitroimidazole resistance plasmid pIP417 from Bacteroides vulgatus BV-17: characterization and nucleotide sequence analysis of the mobilization region.

Three small 5-nitroimidazole (5-Ni) resistance plasmids (pIP417, pIP419, and pIP421) from Bacteroides clinical isolates are transferable by a conjugative process during homologous or heterologous matings. The mobilization properties of pIP417 originated from strain BV-17 of Bacteroides vulgatus were studied. The plasmid was successfully introduced by in vitro conjugation into different strains of Bacteroides and Prevotella species and could be transferred back from these various strains to a plasmid-free 5-Ni-sensitive Bacteroides fragilis strain, indicating that in vivo spread of the resistance gene may occur. The transfer of plasmid pIP417 harbored by the Tc(r) strain BF-2 of B. fragilis was stimulated by low concentrations of tetracycline or chlorotetracycline. This suggests a possible role for coresident conjugative transposons in the dissemination of 5-Ni resistance among gram-negative anaerobes. The nucleotide sequence of the 2.1-kb DNA mobilization region was determined. It contains a putative origin of transfer (oriT) in an A+T-rich-region, including three inverted repeats, and two integration host factor binding sites. The two identified mobilization genes (mobA and mobB) are organized in one operon and were both required for efficient transfer. Southern blotting indicated that the mobilization region of plasmid pIP417 is closely related to that of both the erythromycin resistance plasmid pBFTM1O and the 5-Ni resistance plasmid pIP419 but not to that of the 5-Ni resistance plasmid pIP421.

When can the Ogston-Morris-Rodbard-Chrambach model be applied to gel electrophoresis?

The Ogston-Morris-Rodbard-Chrambach theory of gel electrophoresis is consistent with predictions from the volume averaging method with respect to the equivalence of the accessible volume fraction to the ratios of gel mobility to free solution mobility and the gel diffusion coefficient to free solution diffusion coefficient for the limiting case of small molecule electrophoresis with low electrical fields, low gel concentrations, and nonconductive gel fibers. When these conditions are not valid, more extensive calculations are required to determine the mobility and diffusion coefficient ratios as functions of the geometry and electrical field within the gel. The volume averaging theory shows that it is important to account for the electrical conductivity properties of the fibers that make up a gel electrophoresis medium, and this aspect is consistent with early theories of transport phenomena in gel electrophoresis.

Genetic analysis of the minimal replicon of plasmid pIP417 and comparison with the other encoding 5-nitroimidazole resistance plasmids from Bacteroides spp.

The nucleotide sequence of the DNA replication origin region of a Bacteroides vulgatus plasmid, pIP417, encoding 5-nitroimidazole resistance has been determined. This region of 1934 bp presents some characteristics similar to those of other replication protein-dependent origins. It contains a large open reading frame which could encode a basic Rep protein (RepA) of 36.8 kDa. Upstream of this ORF exist an AT-rich region, three direct repeats (iterons) of 21 bp, multiple DnaA binding sites, and sites, and sites for the integration host factor (IHF). Moreover, the amino acid sequence of the pIP417 RepA protein shows similarities with those of other Rep proteins encoded by plasmids of gram-negative bacteria: pRO1600 from Pseudomonas aeruginosa; pPS10 from Pseudomonas syringae; pFA3 from Neisseria gonorrhoeae; and two cryptic plasmids from Campylobacter hyointestinalis and Butyrivibrio fibrisolvens. Although RepA can be expressed in an Escherichia coli in vitro transcription-translation assay, vectors containing the pIP417 replication origin did not replicate in E. coli. The homology of the pIP417 replication region with the corresponding regions of other Bacteroides spp, plasmids was also studied by Southern blot hybridization. The results indicated that the repA gene of plasmid pIP417 is homologous to that of plasmid pIP421, but not of plasmid pIP419. The replication region of plasmid pIP421 was sequenced and showed about 80% identity at the nucleotide level with that of pIP417. A small (3634-bp) cloning vector (pFK12) of entirely defined nucleotide sequence was constructed for Bacteroides spp.

Plasmids pIP419 and pIP421 from Bacteroides: 5-nitroimidazole resistance genes and their upstream insertion sequence elements.

The genetic organization of two different 5-nitroimidazole (5-Ni) resistance genes was investigated: nimC and nimD from Bacteroides plasmids pIP419 and pIP421, respectively. The nimC gene (492 bp) and the nimD gene (495 bp) directed the synthesis of polypeptides with deduced molecular masses of 18.37 kDa and 18.48 kDa, respectively. The predicted proteins showed 67-83% identity and 78-91% similarity with the products of two other nimA and nimB genes previously described and could be derived from a common ancestral gene. An insertion sequence element (IS1170) was identified upstream of the nimC gene. IS1170 is 1604 bp in length and is flanked by imperfect inverted repeats (15 bp). IS1170 is similar to the Bacteroides insertion sequence element IS942 with an identity of 70% at the nucleotide level. The single copy of IS1170 present on plasmid pIP419 is integrated 24 bp upstream of the initiation codon of nimC. Similar genetic organization was found on plasmid pIP421. One copy of another insertion sequence (IS1169) was found 4 bp upstream of the first ATG codon of the nimD gene. This element (1325 bp) shows a strong homology at the nucleotide level (70% identity) with IS1186 and IS1168 found to be associated with the Bacteroides carbapenem resistance gene cfiA, and the 5-Nirgenes nimA and nimB, respectively. There is strong evidence that, as in the case of the cfiA gene, the transcription of the four nim genes so far studied is directed by outward-oriented promoters, carried on the right ends of the different insertion sequence elements.

[Additive effects of carboplatin (CBDCA) and Co-60 gamma rays in human tumor cells in vitro]. / Additive Effekte zwischen Carboplatin (CBDCA) und 60Co-Gammastrahlen in humanen Tumorzellinien in vitro.

In vitro investigations on the combination effect of radiation and carboplatin (CBDCA) in three human cell lines (HeLa, MRI-186 Caski) show purely additive effects. Study of the molecular lesions gave considerable differences in the time course of repair of radiation induced DNA-double strand-breaks and of formation of DNA-crosslinks by carboplatin. However, sequential treatment with intervals of up to +/- 24 hours resulted also in an additive effect. In the experimental systems studied, a true radiosensitization was not demonstrated.

Measuring growth of a phenanthrene-degrading bacterial inoculum in soil with a quantitative competitive polymerase chain reaction method.

We measured growth of a phenanthrene-degrading bacterium, Arthrobacter, strain RP17, in Forbes soil, amended with 500 µg g(-1) phenanthrene using a quantitative competitive polymerase chain reaction method. The inoculum, which was not indigenous to Forbes soil, grew from 5.55x10(5) colony forming units (cfu) g(-1) to 1.97x10(7) cfu g(-1) within 100 h after the cells were added to the soil. Maximum population density was reached before the highest degradation rate was observed 150 h after the cells were added to soil. Population density remained stable even after 56% of the phenanthrene had mineralized. This study is one of the few documented examples of growth by a non-indigenous bacterium in a non-sterile soil amended with a pollutant.