Tetrodecamycin (1) is a novel α-(γ-hydroxyacyl) tetronic acid based polyketide antibiotic isolated from the culture broth of Streptomyces nashvillensis MJ885-mF8 by Takeuchi et al. in 1994. Compound 1 shows potent inhibitory activity against Gram-positive bacteria including Bacillus anthracis and methicillin resistant Staphylococcus aureus (MRSA). It was proposed that an Aldol reaction of trans-decalin core 2 and tetronic acid derivative 3 followed by a face selective epoxidation and a subsequent epoxide-opening reaction would deliver the 6,6,7,5-skeleton of tetrodecamycm (1). To investigate this proposal, the silyl enol ether 5 was prepared from cycloheptene 4 in 7 steps. An unusual domino silyl enol ether reaction sequence was observed when the silyl enol ether 5 was submitted to a Diels-Alder reaction. It afforded cycloadduct 6, which was converted to the key intermediate 2 after another 3 steps (Scheme 1). Concurrently, double functionalisation of simple cyclic silyl enol ethers was investigated. Because of some difficulties in reproducing good overall yields to the cycloadduct 6, a second synthetic route was proposed. It was envisaged that a palladium-catalysed oxidative cyclisation or an organoselenium-mediated cyclisation reaction of compound 8 would construct the 6,6,7,5- skeleton 7, which would be converted to tetrodecamycin (1) via dihydroxylation followed by an introduction of the exo-methylene group. The intramolecular Diels-Alder reaction of trienal 11 afforded trans-decalin 10, which was converted to β-keto ester 9 in 2 steps. A Dieckmann-type cyclisation of 9 afforded compound 8 in good yield. However, so far transformation to compound 7 has not been achieved (Scheme 2).

This work deals with channel-tunnel dependent multidrug efflux pumps and type I secretion systems, more concrete with the improved classification of the adaptor protein family, the characterization of the TolC-homologue protein HI1462 of Haemophilus influenzae, and the molecular characterization of the interaction between TolC and AcrA of Escherichia coli. / Diese Arbeit beschäftigt sich mit Channel-Tunnel-abhängigen Multidrug Efflux Pumpen und Typ I Sekretionssystemen, genauer gesagt mit der verbesserten Klassifikation der Familie der Adapter-Proteine, der Charakterisierung des TolC-homologen Proteins HI1462 aus Haemophilus influenzae, und der molekularen Charakterisierung der Interaktion zwischen TolC und AcrA aus Escherichia coli.

A thesis submitted to the Faculty of Medicine, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements of Doctor of Philosophy. Johannesburg 1991 / Trimethoprim is a broad-spectrum antimicrobial agent frequently used either in combination with sulphamethoxazole (cotrimoxazole) or alone in the treatment of urinary and respiratory tract infections. Since the introduction of this drug in 1969 resistance to it has been monitored in several centres in Europe continuously but only intermittently in the United States of America and developing countries in Africa, Asia, Central and South America. In Europe the incidence of trimethoprim resistance has increased significantly in the last 20 years. In developing countries no trends have been established but the incidence of resistance appears to be greater in these countries than in Europe or the USA. / IT2018

A unique undescribed gram-negative rod is extensively characterized in this study. The cells of this unusual water isolate measure 1.2 x 6.5 microns. The most distinguishing characteristic of the bacterium is a polar tuft of 35-40 flagella that aggregate to function as a single organelle which is visible under phase contrast.

A leptospirose é uma zoonose causada por bactérias do gênero Leptospira. A patogênese da doença em humanos é observada principalmente no pulmão, fígado e rins. Neste trabalho, foi avaliado o papel da resposta imune inata na proteção contra a leptospirose usando camundongos como modelo experimental. Os animais foram infectados com L. interrogans e o desenvolvimento da doença foi acompanhado, observando-se a morte de animais C3H/HeJ, enquanto C3H/HePas apresentou icterícia e BALB/c não apresentou sintomas. O perfil de mRNA foi medido por qPCR nas amostras de rim, fígado e pulmão e as concentrações de proteinas TNF-<font face=\"Symbol\">&#945;, TGF-<font face=\"Symbol\">b, MCP-1, MIP-1<font face=\"Symbol\">&#945;, MIP-2 e IL-8 foram analisadas por ELISA em extratos dos tecidos e no soro. Os resultados demonstraram que L. interrogans estimula a expressão prematura de TNF-<font face=\"Symbol\">&#945;, TGF-<font face=\"Symbol\">b, MCP-1, MIP-1<font face=\"Symbol\">&#945;, MIP-2 e IL-8 na linhagem BALB/c resistente à infecção. A análise histológica indica que estes mediadores podem estar relacionados com o influxo de diferentes células do sistema imune desempenhando importantes funções na proteção contra leptospirose. / Leptospirosis is a worldwide zoonosis caused by Leptospira. The pathogenesis in humans is mainly observed in lungs, livers and kidneys. In this work the role of innate immune response in protection against leptospirosis is being studied using different mice models. The animals were infected intraperitoneally with virulent cells of L. interrogans serovar Copenhageni and the development of the disease was followed, being observed mortality of C3H/HeJ mice, whereas C3H/HePas presented jaundice and BALB/c mice remained asymptomatic. Samples of liver, kidney, lungs and sera were analyzed following the profiles of mRNA and protein of the cytokines TNF-<font face=\"Symbol\">&#945; and TGF-<font face=\"Symbol\">b and chemokine MCP-1, MIP-1<font face=\"Symbol\">&#945;, MIP-2 and CXCL1/IL-8. We showed that Leptospira infection stimulates early expression of cytokine TNF-<font face=\"Symbol\">&#945; and TGF-<font face=\"Symbol\">b and chemokine MCP-1, MIP-1<font face=\"Symbol\">&#945;, MIP-2 and IL-8 in the resistant mice strain BALB/c. Histological analysis indicates that the expression of those molecules can be related to the influx of distinct immune cells, which play a role in the naturally acquired protective immunity.

Several bacteria were isolated from the bottom sediments of Tyume River and investigated for bioflocculant production potentials. Kaolin clay suspension (4 g/l) was used to measure the flocculating activity and three of the positive isolates were identified by 16S rRNA gene nucleotide sequence analyses and the sequences deposited in GenBank as Streptomyces sp Gansen (accession number HQ537129), Brachybacterium sp UFH (accession number HQ537131.), and Cellulomonas sp Bola (accession number HQ537132). Streptomyces sp Gansen exhibited its maximum flocculating activity using lactose (85% activity), peptone (76.3% activity), Ca2+ as sole sources of carbon, nitrogen and cations respectively, and at a neutral pH of 7.0, while, the bioflocculant produced by Brachybacterium sp UFH with glucose, urea and Ca2+ as carbon, nitrogen and cations sources yielded 82% and 97% flocculation activity respectively at a neutral pH. Also, glucose (73.2% activity), ammonium chloride (78.2% activity) and Ca2+ resulted in optimal production of bioflocculant by Cellulomonas sp Bola, also at a neutral pH. Chemical analysis confirmed that bioflocculant produced by Streptomyces Gansen is a polysaccharide while Brachybacterium sp UFH and Cellulomonas sp Bola produces a glycoprotein compound. This freshwater actinomycetes appears to have a tremendous potential as sou rces of new bioflocculants.

Burkholderia cepacia complex (Bcc) bacteria reside in soil, plant rhizospheres, and water, but the prevalence of Bcc in outdoor environments is not clear. In this study, we sampled a variety of soil and rhizosphere environments with which people may have contact: playgrounds, athletic fields, parks, hiking trails, residential yards and gardens. A total of 9l soil samples was obtained from three large U.S. cities (Philadelphia, PA, Cleveland, OH, and Portland, OR). In the first phase of the study, putative Bcc isolates were recovered on Burkholderia cepacia selective agar (BCSA) and trypan blue tetracycline medium (TBT). Isolates were sent to the Burkholderia cepacia Referral Laboratory and Repository, where they were identified using biochemical tests, growth at 32��C, and polymerase chain reaction (PCR) assays targeting both rRNA and recA gene sequences. Bcc isolates were genotyped by using RAPD, PFGE and rep-PCR. A total of 1013 bacterial isolates were examined, and 68 were identified as B. cepacia complex. The majority of these were B. pyrrocinia or genomovar VII (B. ambifaria); however, a few genomovar III isolates were also recovered. Fourteen (15%) of 91 soil samples yielded Bcc isolates. In the second phase of the study, DNA was extracted from 87 of the 91 soil samples and examined with PCR assays targeting Bcc 16S rRNA gene sequences. By using assays developed by LiPuma et al. (1999), 82% of the soil samples were positive for at least one Bcc genomovar, whereas 94% of samples were positive for at least one Bce genomovar using the Bauernfeind et al. (1999) assay system. Selected amplicons generated from four soil samples were cloned, and plasmids from multiple transformants (total=120) were screened by RFLP analysis. Among the clones evaluated from three of four soil samples, 90% or more had the "Burkholderia" RFLP pattern. In the remaining soil sample, only 9.5% of the evaluated clones displayed this profile. Sequence analysis of the 463bp 16S rRNA inserts from eight clones with the "Burkholderia" RFLP pattern indicated that all were from members of the Bcc. However, the four soil samples from which these clones were generated did not yield isolates identified as Bcc. This study indicates that the use of selective media may not be the best way to estimate the environmental prevalence of Bcc in soils. The natural populations of Bcc in soils with which people commonly have contact may be much higher than previously estimated. / Graduation date: 2002

Thesis--Washington University (St. Louis). / Musical examples: p. 1-93 (2d group). eContent provider-neutral record in process. Description based on print version record. Bibliography: p. 167-173.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Twenty-three marine and two terrestrial gram-negative bacteria were examined by electron microscopy for the effect on the outer membrane of the cells of washing the organisms successively in 0.5M NaCl and 0.5M sucrose. Six marine bacteria lost their outer membranes completely, three lost large segments but not all of their outer membranes, and six retained their outer membranes but with either gross distortions of the outer membrane and/or segments of outer membrane removed from some cells. The remaining eight marine and two terrestrial bacteria appeared to have continuous outer membranes after application of the wash procedure. / Eighteen of the twenty-three marine bacteria employed in the wash treatment study and two terrestrial bacteria were examined for the effect of washing and suspending the organisms in various solutions with respect to lysis of the cells and Optical Density (O.D.) changes of suspensions. / A spectrum of lytic susceptibility was observed among the marine bacteria ranging from those organisms which lysed in distilled water after exposure to Mg('2+) through organisms which lysed upon suspension in distilled water after pre-exposure to NaCl but which failed to lyse in distilled water if pre-exposed to Mg('2+) to organisms which failed to lyse in distilled water even after exposure to NaCl. E. coli and Ps. aeruginosa also fell within this spectrum. / After exposure to NaCl and subsequent suspension of these organisms in decreasing concentrations of either NaCl, KCl or MgCl(,2), concentrations of KCl two to three times that of NaCl or ten to four hundred times that of MgCl(,2) could protect most marine organisms from lysis or larger decreases in the O.D. of their suspensions. However, three marine and both terrestrial bacteria required only equal concentrations of KCl or NaCl to effect protection. / No overall distinction can therefore be made between marine and terrestrial bacteria with respect to the status of the outer membrane of these organisms after washing them in NaCl and sucrose solutions or the sensitivity of the two groups of organisms to lysis in distilled water after pre-exposure to NaCl or MgCl(,2).