The effect of the novel and potent monofunctional platinum(II) agent phenanthriplatin on Escherichia coli and bacteriophage λ lysogens is reported. E. coli filamentation was observed by light microscopy when cells were grown in the presence of phenanthriplatin, cis-[Pt(NH3)2(Am)Cl]+ where Am is phenanthridine. Treatment of lysogenic bacteria with this compound resulted in lysis and the production of viral particles, as indicated by plaque formation in a bacterial lawn. The results obtained with phenanthriplatin are contextualized by comparison with those obtained using cisplatin as well as other, less active, monofunctional compounds such as [Pt(NH3)3Cl]+ and cis-[Pt(NH3)2(py)Cl]+, where py is pyridine. The ability of phenanthriplatin to induce bacterial filamentation and initiate lysis in lysogenic bacteria corroborates the hypothesis that the biological activity of this complex is mediated by its interaction with DNA.
A series of Pt(IV) prodrugs has been obtained by oxidative halogenation of either cisplatin or carboplatin. Iodobenzene dichloride is a general reagent that cleanly provides prodrugs bearing axial chlorides without the need to prepare intervening Pt(IV) intermediates or handle chlorine gas. Elemental bromine and iodine afford Pt(IV) compounds as well, although in the case of the iodine-mediated oxidation of carboplatin, an amido-bridged Pt(IV) side product also formed. A detailed analysis of the changes in spectroscopic and structural parameters induced by varying the axial halide is presented. A number of recurring motifs are observed in the solid state structures of these compounds.
The molecular diversity among 60 isolates of Renibacterium salmoninarum which differ in place and date of isolation was investigated by using randomly amplified polymorphic DNA (RAPD) analysis. Isolates were grouped into 21 banding patterns which did not reflect the biological source. Four 16S-23S rRNA intergenic spacer (ITS1) sequence variations and two alleles of an exact tandem repeat locus, ETR-A, were the bases for formation of distinct groups within the RAPD clusters. This study provides evidence that the most common ITS1 sequence variant, SV1, possesses two copies of a 51-bp repeat unit at ETR-A and has been widely dispersed among countries which are associated with mainstream intensive salmonid culture.Renibacterium salmoninarum is an important cause of clinical and subclinical infections among farmed and wild salmonid populations in North and South America, Europe, and Japan (5). The organism causes a chronic, systemic, and granulomatous infection, bacterial kidney disease (BKD), that is often fatal under conditions which are stressful to the host (11). There is no effective vaccine or chemotherapy, and the presence of subclinical infections complicates attempts to control the disease through programs of eradication. An improved understanding of the transmission and spread of BKD is of considerable importance in policy management issues relating to aquaculture and wildfisheries. There have been a number of studies investigating the presence, prevalence, and means of transmission of BKD within and between fish populations. This work has shown that R. salmoninarum is endemic within many wild salmonid populations as a low-level, subclinical infection; it has been isolated in up to 100% of samples (9,12,15). However, the epidemiology of BKD remains unclear, mainly because of the difficulty of differentiating isolates of R. salmoninarum by biochemical, serological, and multilocus enzyme electrophoresis techniques (1,6,16).We used two approaches to assess the extent of molecular variation among R. salmoninarum isolates from different geographic locations. First, we investigated possible polymorphisms in specific regions within the genome, genes msa (3), rsh (4), and hly (8), and the rRNA genes, including the intergenic spacer (ITS) regions. PCR and DNA sequencing studies have shown that R. salmoninarum has only limited variation in these regions (7). Identifying specific markers of variation in the R. salmoninarum genome, such as insertion sequences or variable numbers of tandem repeats (TR), has been constrained by a paucity of sequence information. Second, we analyzed differences throughout the genome using randomly amplified polymorphic DNA (RAPD) analysis. RAPD analysis is a PCR-based alternative method to the use of species-specific DNA sequences for isolate or strain differentiation. The method uses short random primers for rapidly detecting genomic polymorphisms under low-stringency conditions (18,19). RAPD analysis is widely used for differentiating bacterial isolates (2, 10, 17) and relies on small q...
A means for distinguishing between clinical isolates of Renibacterium salmoninarum that is based on the PCR amplification of length polymorphisms in the tRNA intergenic spacer regions (tDNA-ILPs) was investigated. The method used primers specific to nucleotide sequences of R. salmoninarum tRNA genes and tRNA intergenic spacer regions that had been generated by using consensus tRNA gene primers. Twenty-one PCR products were sequenced from five isolates of R. salmoninarum from the United States, England, and Scotland, and four complete tRNA genes and spacer regions were identified. Sixteen specific PCR primers were designed and tested singly and in all possible pairwise combinations for their potential to discriminate between isolates from recent clinical outbreaks of bacterial kidney disease (BKD) in the United Kingdom. Fourteen of the isolates were cultured from kidney samples taken from fish displaying clinical signs of BKD on five farms, and some of the isolates came from the same farm and at the same time. The tDNA-ILP profiles separated 22 clinical isolates into nine groups and highlighted that some farms may have had more than one source of infection. The grouping of isolates improved on the discriminatory power of previously reported typing methods based on randomly amplified polymorphic DNA analysis and restriction fragment length profiles developed using insertion sequence IS994. Our method enabled us to make divisions between closely related clinical isolates of R. salmoninarum that have identical exact tandem repeat (ETR-A) loci, rRNA intergenic spacer sequences, and IS994 profiles.
Background Distribution of long-lasting insecticide treated nets (LLINs) is the most widely used intervention for the prevention of malaria but recall and social desirability biases may lead to challenges in accurately measuring use of bednets. SmartNet is a remote electronic monitor that provides objective measurements of bednet use over weeks at a time. Assessing local acceptability is important when implementing innovative global health technologies such as SmartNet. This study draws on established models such as the Technology Acceptance Model (TAM) and Theoretical Framework of Acceptability (TFA) to assess acceptability of SmartNet in Ugandan households. Methods Semi-structured qualitative interviews were conducted at weeks one and six following installation of SmartNet in ten households in Western Uganda. Heads-of-households answered open-ended questions addressing the main acceptability domains of the TFA and TAM models (i.e. perceived ease of use, ethicality, etc.). Responses were digitally recorded, transcribed, coded and analyzed using a thematic analysis approach. Results Seven out of ten households interviewed reported no difference in use between SmartNet and a standard LLIN. Households stated the large size, soft fabric, and the efficacy of SmartNet relative to a standard LLIN contributed to perceived usefulness and perceived ease of use. Opportunity costs of the novel monitoring system expressed by households included difficulty washing nets and dislike of blinking lights on the device. Barriers to SmartNet use focused on questions of the ethics of bednet use monitoring, discomfort with technical aspects of the device and a poor understanding of its function amongst others in the community. However, explaining SmartNet to other community members resolved these concerns and often resulted in interest and acceptance among peers. Conclusion Objective monitoring of bednet use with SmartNet appears acceptable to these households in Uganda. Use of SmartNet seems to be similar to behaviors around use of standard LLINs. Viewpoints on many aspects of SmartNet were generally favorable. Concerns around ethicality of bednet monitoring are present and indicate the need for continuing community education. The device will continue to be optimized to make it more acceptable to users and to accurately reflect standard LLIN use to improve our understanding of prevention behaviors in malaria endemic settings.
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