The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
David Taylorrobinson - One of the best experts on this subject based on the ideXlab platform.
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mollicutes in vaginal microbiology Mycoplasma hominis ureaplasma urealyticum ureaplasma parvum and Mycoplasma genitalium
Research in Microbiology, 2017Co-Authors: David TaylorrobinsonAbstract:Abstract Mycoplasma hominis was isolated in 1937 from the human genital tract, followed 17 years later by Ureaplasma urealyticum and 27 years after that by Mycoplasma genitalium. The first two proved relatively easy to culture but the latter required a polymerase chain reaction assay for further studies. In sexually mature women, M. hominis may be found in the vagina/cervix of about 20–50%, ureaplasmas in 40–80% and M. genitalium in 0–5%. Some heterogeneity has been found among strains of all these species, sufficient to divide ureaplasmas into two species, namely U. urealyticum and Ureaplasma parvum. Studies in female mice show that sex hormones have a profound influence on colonization, multiplication and persistence of Mycoplasmas/ureaplasmas in the genital tract and provoke the question, unanswered, of whether there is such an effect in the human tract. In women, there is no evidence that any of the Mycoplasmal species stimulate an inflammatory vaginitis. M. hominis organisms increase hugely in number in the case of bacterial vaginosis (BV), and to a lesser extent so do ureaplasmas. Despite this, they have not been incriminated as a sole cause of BV. Evidence for the involvement of M. genitalium remains controversial. The strong association of BV with preterm birth raises the possibility that the genital Mycoplasmas might play a part, but assurance that any do will be difficult to obtain. Detailed examination of the vaginal microbiome has not yet provided an answer.
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Mycoplasma fermentans in individuals seropositive and seronegative for hiv 1
The Lancet, 1993Co-Authors: V Katseni, B K Ryait, Koya Ariyoshi, David Taylorrobinson, J. Weber, C B GilroyAbstract:Abstract Mycoplasmas have been suggested as a co-factor to explain various puzzling features of infection by human immunodeficiency virus 1 (HIV-1). We sought Mycoplasma fermentans by means of a semi-nested polymerase chain reaction (PCR) in samples of peripheral-blood mononuclear cells (PBMC), throat swabs, and urine samples from 117 HIV-seropositive patients (of whom 114 were homosexual men). Mfermentans was detected in 12 (10%) PBMC samples, 15 (23%) of 65 throat samples, and 4 (8%) of 55 urine samples from the seropositive subjects. The organism was detected in similar proportions among 73 HIV-seronegative patients recruited from a sexually transmitted diseases clinic (9%, 20%, and 6%, respectively); again, most of the men (40 of 50) in this group were homosexual. We found no association between infection by the Mycoplasma and stage of disease, CD4 count, or HIV-1 load. These findings do not, however, eliminate the possibility that the Mycoplasmal infection could affect the speed of disease progression.
Yehudith Naot - One of the best experts on this subject based on the ideXlab platform.
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Molecular Biology and Pathogenicity of Mycoplasmas - Molecular Biology and Pathogenicity of Mycoplasmas
Microbiology and molecular biology reviews : MMBR, 1998Co-Authors: Shmuel Razin, David Yogev, Yehudith NaotAbstract:The recent sequencing of the entire genomes of Mycoplasma genitalium and M. pneumoniae has attracted considerable attention to the molecular biology of Mycoplasmas, the smallest self-replicating organisms. It appears that we are now much closer to the goal of defining, in molecular terms, the entire machinery of a self-replicating cell. Comparative genomics based on comparison of the genomic makeup of Mycoplasmal genomes with those of other bacteria, has opened new ways of looking at the evolutionary history of the Mycoplasmas. There is now solid genetic support for the hypothesis that Mycoplasmas have evolved as a branch of gram-positive bacteria by a process of reductive evolution. During this process, the Mycoplasmas lost considerable portions of their ancestors’ chromosomes but retained the genes essential for life. Thus, the Mycoplasmal genomes carry a high percentage of conserved genes, greatly facilitating gene annotation. The significant genome compaction that occurred in Mycoplasmas was made possible by adopting a parasitic mode of life. The supply of nutrients from their hosts apparently enabled Mycoplasmas to lose, during evolution, the genes for many assimilative processes. During their evolution and adaptation to a parasitic mode of life, the Mycoplasmas have developed various genetic systems providing a highly plastic set of variable surface proteins to evade the host immune system. The uniqueness of the Mycoplasmal systems is manifested by the presence of highly mutable modules combined with an ability to expand the antigenic repertoire by generating structural alternatives, all compressed into limited genomic sequences. In the absence of a cell wall and a periplasmic space, the majority of surface variable antigens in Mycoplasmas are lipoproteins. Apart from providing specific antiMycoplasmal defense, the host immune system is also involved in the development of pathogenic lesions and exacerbation of Mycoplasma induced diseases. Mycoplasmas are able to stimulate as well as suppress lymphocytes in a nonspecific, polyclonal manner, both in vitro and in vivo. As well as to affecting various subsets of lymphocytes, Mycoplasmas and Mycoplasma-derived cell components modulate the activities of monocytes/macrophages and NK cells and trigger the production of a wide variety of up-regulating and down-regulating cytokines and chemokines. Mycoplasma-mediated secretion of proinflammatory cytokines, such as tumor necrosis factor alpha, interleukin-1 (IL-1), and IL-6, by macrophages and of up-regulating cytokines by mitogenically stimulated lymphocytes plays a major role in Mycoplasma-induced immune system modulation and inflammatory responses.
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Mycoplasmas as Immunomodulators
Rapid Diagnosis of Mycoplasmas, 1993Co-Authors: Yehudith NaotAbstract:Following successful adherence and colonization of host tissues by invading Mycoplasmas, interactions between organisms and their host immune system are initiated. Specific, protective antiMycoplasmal humoral and cellular immune responses are often only partially effective, thus leading to a chronic persistent infection. In addition, Mycoplasmas can induce nonspecific modulation of host immune responses thereby contributing to the immuno-pathological manifestations of Mycoplasmal infections. Nonspecific suppression of host immune responses may affect the host’s capacity to eradicate the evading Mycoplasma and it also may render the host more susceptible to infections with other microorganisms. On the other hand, nonspecific-mitogenic activation of host immune mechanisms may be responsible for the massive cellular responses, lymphoid hyperplasia, cell infiltration, inflammation and chemotactic phenomena which often characterize Mycoplasma infections. It is obvious that the immune mechanisms operating during any Mycoplasma infection are complex and depend on both the Mycoplasma species and the infected host. It is therefore crucial to clarify in each case the nature of specific as well as nonspecific interactions between the invading Mycoplasma and its host immune cells. This paper will address the capacity of Mycoplasmas to modulate immune responses either by suppression or by nonspecific activation.
Timenetsky Jorge - One of the best experts on this subject based on the ideXlab platform.
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Sensibilidade de fibrocondrócitos de coelhos a micoplasmas
Sociedade Brasileira de Microbiologia, 2002Co-Authors: Nascimento, Carlos Manuel De Oliveira, Figueiredo, Cristina Adelaide, Timenetsky JorgeAbstract:Primary cell culture from rabbit meniscus (fibrochondrocytes-FcrC) was infected for 24 hours with different inocula (10² to 10(7) Colony Forming Units-CFU) of Mycoplasma hominis PG-21, M. pneumoniae FH and 1428 or M. arthritidis PG-6. The severity of the different obtained cytophatic effects-CPE was inoculum, Mycoplasma species and strain dependant. These bacteria were recovered from all infected FcrC and the SP4 medium for Mycoplasmas also caused toxic effect on the FcrC. It was concluded that rabbit fibrochondrocytes were sensitive to Mycoplasma infection, as well as to the SP4 Mycoplasma medium.Cultura primária de menisco de coelho (Fibrocondrócito-FcrC) foi infectada por 24 horas com diferentes inóculos (10² to 10(7) Unidade Formadoras de Colonias-UFC) de Mycoplasma hominis PG-21, M. pneumoniae FH e 1428 ou M. arthritidis PG-6. A severidade dos diferentes efeitos citopáticos-EC foram dependentes do inóculo, espécie e cepa de micoplasma. Estas bactérias foram reisoladas de todos os FcrC infectados e o meio SP4 para micoplasmas também causou efeito tóxico para os FcrC. Concluiu-se que os fibrocondrócitos de coelho foram sensíveis à infecção por micoplasmas e também ao meio SP4
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Mycoplasma pulmonis e/ou Mycoplasma arthritidis em animais de laboratório (ratos e camundongos) de diferentes biotérios
Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia, 1992Co-Authors: Timenetsky Jorge, Summa, Maria Eugenia Laurito, Rosália Regina De ,luccaAbstract:Ratos e camundongos de três biotérios com e um sem barreiras microbianas foram bacteriologicamente estudados quanto à presença de micoplasma, através da perfusão de pulmão com lavado traqueobrônquico e lavado de ouvido. Caracterizou-se a presença destas bactérias pela formação de colônias em "ovo frito", coloração de Dienes, resistência à digitonina, catabolismo da glicose, hidrólise da arginina, redução do tetrazólio e produção de filme e manchas. A identificação das cepas isoladas foi através da inibição de crescimento. No biotério com barreiras microbianas, os micoplasmas não foram detectados. Entretanto, isolou-se Mycoplasma pulmonis e Mycoplasma arthritidis em biotérios sem barreiras. Nas instalações sem barreiras microbianas com amostragem representativa, detectou-se M. pulmonis em 20% dos camundongos Swiss, 14,28% na linhagem C57B1/6J e em 83,78% na amostragem dos ratos. Encontrou-se M. arthritidis em 5,4% dos ratos, através da lavagem de ouvido. Ambas as espécies estavam presentes em 2,7% dos ratos. Os anti-soros utilizados não identificaram uma cepa isolada de hamster. M. pulmonis foi identificado em ratos de um grupo de animais procedentes de outros 2 biotérios. A taxa de infecção por micoplasma não pôde ser estabelecida porque os ratos e camundongos foram especialmente selecionados para a pesquisa de micoplasma devido a sua origem a aspectos clínicos. Os autores sugerem que a pesquisa de micoplasma em animais de laboratório seja freqüente, com amostragem representativa e com a identificação destes microrganismos para o aprimoramento de seu controle.Rats and mice from different animal house facilities without microbial barriers and one from barrier sustained facilities were checked for Mycoplasma presence by lung perfusion with tracheobronquial lavage and ear flushing. Mycoplasmas were characterized by "fried egg" colonies, Dienes stain and digitonine resistance. Glucose catabolism, arginine hydrolysis, tetrazoliun reduction and film/ spots production was applied as screening differential assays. Identification was performed by growth inhibition test. In the barrier sustained colonies, Mycoplasmas were not detected, but from a conventional animal house, M. pulmonis was found in the follow order: 20.0% in Swiss mice, 14.28% in C57BL/6J colonies and 83.79% in Wistar rats. M. arthritidis was isolated only from rats by ear flushing in order of 5.4%. Both species were observed in one rat and one unidentified strain of mycolplasma was isolated from hamsters. M. pulmonis was obtained from rats but not from mice proceeded from other two conventional animal houses. Mycoplasma infection rate could not be established in these facilities because rats and mice were specially selected, as usually is to search Mycoplasmas, based on their origin and symptoms. The authors suggest that Mycoplasma investigation nust be permanent in any animal house rearing rodents. Mycoplasma infection rate must be established with a representative sampling not including only sick animals
Innokentii E. Vishnyakov - One of the best experts on this subject based on the ideXlab platform.
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Recombinant FtsZ Proteins from Mollicutes Interact with Escherichia coli Division Machinery
BioNanoScience, 2016Co-Authors: Alexey D. Vedyaykin, Anton V. Sabantsev, Mikhail A. Khodorkovskii, Airat R. Kayumov, Innokentii E. VishnyakovAbstract:FtsZ is a well-known prokaryotic tubulin homologue. It participates in cytokinesis in most bacteria and is considered to be a key division protein. However, the genomes of some Mycoplasma species (class Mollicutes) lack of the ftsZ genes or even ftsZ- like genes. Moreover, it was demonstrated for Mycoplasma mycoides and Mycoplasma genitalium that FtsZ protein is not essential for division and survival. In this study, we induced an expression of recombinant FtsZ proteins from Mollicutes Acholeplasma laidlawii and Mycoplasma gallisepticum in Escherichia coli cells in the background of normal expression of its own FtsZ. By using indirect double immunofluorescence in combination with single-molecule localization microscopy, it was demonstrated that both Mycoplasmal FtsZ proteins are able to interfere with E. coli division machinery, but the interaction differs depending on the protein used. Our data suggest that FtsZ proteins from Mollicutes may play an important role in the cell division of corresponding Mycoplasmas.
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Mycoplasma Diversity in Arctic Permafrost
BioNanoScience, 2016Co-Authors: Innokentii E. Vishnyakov, Airat R. Kayumov, Sergei N. Borchsenius, Elizaveta M. RivkinaAbstract:Viable bacterial cells and its genetic material can be stably maintained in Arctic permafrost for a long geological time. Because of the seasonal melting of permafrost strata, it cannot be excluded an access to the surface of ancient highly invasive species with increased pathogenicity. Mycoplasmas are very successful pathogens in humans, mammals, birds, insects, and plants, with high genome plasticity and ability to avoid immune response of host organism. The metagenomic approach allowed us to predict Mycoplasma diversity in the Arctic permafrost. The number of Mycoplasma DNA fragments in soil deposits of comparable age (∼30,000 years) and origin (the late Pleistocene Ice Complexes) is not so abundant compared with other microorganisms, but it is enough for a chance in the presence of living Mycoplasmal cells in permafrost. DNA fragments of human, animal, insect, and plant pathogens were identified. The “ubiquitous” Mycoplasma Acholeplasma laidlawii is the undisputed leader in the number of identified sequences in all three metagenomes. It may indicate a higher adaptive capacity and more powerful metabolic potential of A. laidlawii among Mollicutes.
Kim S Wise - One of the best experts on this subject based on the ideXlab platform.
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the Mycoplasma fermentans prophage φmfv1 genome organization mobility and variable expression of an encoded surface protein
Molecular Microbiology, 2004Co-Authors: Kerstin Roske, Michael J Calcutt, Kim S WiseAbstract:: The approximately 16 kb genome of the Mycoplasma fermentans phiMFV1 prophage is described, and its mobility, replication and effect on the Mycoplasma surface phenotype are demonstrated. In various M. fermentans strains, phiMFV1 was either absent or integrated at diverse (and sometimes multiple) chromosomal sites, each marked by a conserved TTTTTA target sequence that is duplicated upon integration. Precise excision, replication of an extrachromosomal form and loss of phiMFV1 from the Mycoplasmal genome were documented in a series of clonal derivatives of M. fermentans propagated in culture. Of 18 open reading frames (ORFs) encoded by phiMFV1, most can be ascribed functions related to phage biology, whereas one encodes a unique coiled-coil membrane surface protein, Mem, that was confirmed to be expressed in propagating populations of M. fermentans. With the exception of Mem and other minor ORFs, the striking similarity between the deduced proteomes of phiMFV1 and the recently described phiMAV1 of arthritogenic strains of Mycoplasma arthritidis, along with the prominent gene synteny between these elements, provides the taxonomic basis for a new family of prophage. Their coding features are consistent with long-term residence in Mycoplasma genomes and the divergence of species within a phylogenetic clade of Mycoplasmas. The unique Mem protein expressed from phiMFV1 and the unique hypothetical surface lipoproteins encoded by phiMAV1 and phiMFV1 also suggest that prophage-associated genes may provide specific, selectable phenotypic traits during co-evolution of Mycoplasma species with their respective mammalian hosts. Retention of these labile prophage elements in organisms with such drastically reduced genome sizes implies a significant role in adaptation and survival.
