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Results for “Potential pathogens”

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At least 253 records · Page 14Linked to original sources
PubMed2000

Apoptosis in mitochondrial encephalomyopathies with mitochondrial DNA mutations: a potential pathogenic mechanism.

Mitochondrial encephalomyopathies caused by mitochondrial DNA (mtDNA) defects are a genetically and phenotypically heterogeneous group of disorders. The site, percentage and distribution of mutations do not explain the overall clinical heterogeneity that is found. Apoptosis (programmed cell death) is an evolutionarily conserved mechanism that is essential for tissue development and homeostasis. Dysregulation of apoptosis has been implicated in the pathogenesis of various human diseases, such as cancer and autoimmune and neurodegenerative disorders. Recent in vitro evidence has indicated the central role of mitochondria in the apoptotic process. We investigated the occurrence of apoptosis in muscle biopsies of 36 patients carrying different mtDNA mutations and four patients with inclusion body myositis and mitochondrial abnormalities. Apoptotic features, mainly localized in cytochrome c oxidase-negative fibres, were observed in muscle fibres of patients carrying a high percentage of single mtDNA deletions (>40%) and of tRNA point mutations (>70%). By contrast, no apoptotic changes were observed in inclusion body myositis and in patients carrying mutations of mtDNA structural genes. Our study suggests that apoptosis is not simply a means whereby cells with dysfunctional mitochondria are eliminated, but that it seems to play a role in the pathogenesis of mitochondrial disorders associated with mtDNA defects affecting mitochondrial protein synthesis. The imbalance and relative abundances of nuclear-encoded and mtDNA-encoded subunits may favour cytochrome c inactivation and release. Cytochrome c, together with respiratory chain dysfunction, could activate apoptotic pathways that, in turn, inhibit the rate of mitochondrial translation and the importation of nuclear-encoded mitochondrial protein precursors. This vicious circle may amplify the biochemical defects and tissue damage and contribute to the modulation of clinical features.

Adolescent↗
PubMed1995

Construction of a herpes simplex virus/varicella-zoster virus (HSV/VZV) thymidine kinase recombinant with the pathogenic potential of HSV and a drug sensitivity profile resembling that of VZV.

A recombinant of herpes simplex virus (HSV) was constructed in which the HSV thymidine kinase (TK) gene was deleted and the varicella-zoster virus (VZV) TK gene was introduced into the US5 region under the control of the human cytomegalovirus IE promoter. Infection with the recombinant (R18) led to the induction of TK although the kinetics of synthesis resembled those of a 'late' gene product. The recombinant was virulent in the zosteriform mouse model with the pattern of pathogenesis similar to that of wild-type HSV-1. The sensitivity of the recombinant to several nucleoside analogues was assessed and in most cases (BVaraU, ACV and GCV) it resembled VZV rather than HSV. The enhanced sensitivity of the recombinant to BVaraU compared with wild-type HSV resulted in a far greater response to treatment with BVaraU as assessed in the mouse model.

Acyclovir↗
PubMed1995

Potential pathogenic properties of members of the "Streptococcus milleri" group in relation to the production of endocarditis and abscesses.

The "Streptococcus milleri" (SMG) group have been shown to possess factors in vitro that may be involved in pathogenesis. All SMG strains are able to bind fibronectin via a cell-surface protein; the binding ranged from 12 to 198 mol/cell. Strains also bound to platelet-fibrin or fibrin clots and fibrinogen, giving maximum adhesion values of 16.5%, 21.8% and 151 mol/cell respectively. Members of the species S. constellatus produced thrombin-like activity. Lancefield group C SMG aggregated rat platelets, a bacterial cell-surface protein acting as mediator in the reaction. Most of the in-vitro factors did not correlate with each other, an indication that SMG strains possess a wide variety of pathogenic properties that may be involved in the production of abscesses or endocarditis. However, there was a correlation between the binding of large amounts of fibrinogen ( > 100 mol/cell) and the ability to aggregate platelets. This suggests that fibrinogen binding may aid in platelet aggregation.

Abscess↗
PubMed2004

Amycolatopsis palatopharyngis sp. nov., a potentially pathogenic actinomycete isolated from a human clinical source.

The taxonomic position of an actinomycete, strain 1BDZ(T), isolated from a clinical human source was determined using a polyphasic approach. Phylogenetic analysis based on almost complete 16S rDNA sequences showed that this organism consistently formed a distinct line with the Amycolatopsis methanolica subclade within the genus Amycolatopsis, and shared moderately low 16S rDNA similarity (<96.5 %) with other species. The organism was also found to have chemical and morphological properties typical of members of the genus Amycolatopsis. A range of phenotypic characteristics readily distinguished this strain from representatives of all species of Amycolatopsis with validly published names. On the basis of these data, a novel species, Amycolatopsis palatopharyngis sp. nov., is proposed to accommodate strain 1BDZ(T) (=AS 4.1729(T)=PCM 2600(T)).

Actinomycetales↗
PubMed2004

A virulence-associated gene microarray: a tool for investigation of the evolution and pathogenic potential of Staphylococcus aureus.

An oligonucleotide probe microarray for investigation of the evolution of epidemic Staphylococcus aureus strains has been constructed. The array comprises 383 probes based on virulence-associated genes present in four key strains. Twelve strains including seven for which the complete chromosomal nucleotide sequence was available were tested on the array. Twenty-six per cent of the probes were able to differentiate between strains to give a minimum of two gene differences between pairs. A gene difference distance tree based on the array data had approximately the same topology as one prepared using concatenated MLST sequences. Differences in the topologies of these trees were found to indicate that large-scale recombination events had occurred during the evolution of the species. One such occurrence appears to have been a key event in the genesis of the EMRSA-15 clone (ST22) that currently represents the most prevalent methicillin-resistant S. aureus (MRSA) in the UK.

Bacterial Proteins↗
PubMed1995

The effect of sodium hypochlorite on potential pathogenic traits of Candida albicans and other Candida species.

Strains of Candida albicans, Candida krusei, Candida kefyr, Candida tropicalis, Candida parapsilosis and Candida guilliermondii were grown in the presence or absence of concentrations of sodium hypochlorite below the minimal inhibitory concentration and tested for a range of characteristics that may be associated with pathogenicity. Sodium hypochlorite is used routinely in hospitals in Australia for disinfection procedures, and these experiments were designed to assess the efficacy of hypochlorite as a sterilizing agent for acrylic dentures. Candida showed varying abilities to adhere to surfaces that may be present in the oral cavity. Sodium hypochlorite reduced the adhesion of all C. albicans strains and most other Candida species to both polystyrene and buccal epithelial cells. A biofilm of Streptococcus gordonii reduced the adhesion of most C. albicans strains and most other Candida species to polystyrene. However, Candida species were able to coaggregate with S. gordonii in suspension, with one strain of C. albicans, GDH 2346, showing greater coaggregating ability than the other strains or species. Sodium hypochlorite increased coaggregation of all C. albicans strains and most other Candida species. Examination of cell wall proteins from strains of C. albicans and a strain of C. parapsilosis showed that growth in hypochlorite increased the amount of protein in some existing bands and, in one strain of C. albicans, increased the number of detectable protein bands ranging from 56 to 26 kDa. Only 4 strains of C. albicans were able to produce hyphae, and 3 of these same strains and C. parapsilosis were able to produce proteinase. Hypochlorite increased the rate of blastospore to hyphal transition but had no effect on proteinase production or activity. It is concluded that hypochlorite at a concentration below the minimal inhibitory concentration may function as an anti-adhesin for Candida species but may not affect their more pathogenic characteristics.

Acrylic Resins↗
PubMed2002

Environmental investigation of potentially pathogenic Vibrio parahaemolyticus in the Seto-Inland Sea, Japan.

Seawater and organic material (live and/or dead matter deposited on any substratum submersed in seawater) were collected during the cool weather season from a coast of the Seto-Inland Sea, Japan, and analyzed to determine Vibrio parahaemolyticus densities and the occurrence of pathogenic strains, defined as those possessing tdh and/or trh genes by the polymerase chain reaction (PCR), using isolated DNA from enrichment culture of the samples. About 95% of the samples were positive for V. parahaemolyticus (with densities of 3 to >1400 cells per 100 ml water or 10 g organic samples) by the most-probable-number (MPN)-PCR technique with species-specific toxR primers, but only 40% were positive by the conventional MPN-culture technique (with densities ranging from 3 to 240 cells per 100 ml water or 10 g organics). Furthermore, the tdh and trh genes were positive in 55% and 20% of samples, respectively, by the MPN-PCR technique. No tdh and trh gene-positive strains were isolated by the conventional MPN-culture procedure. The difference in detection between the MPN-culture and the MPN-PCR techniques appeared to be significant and may be attributed to different detection sensitivities and other factors.

Bacterial Proteins↗
PubMed2002

Pathogenic potential of fifty Bacillus weihenstephanensis strains.

The aim of this study was to evaluate the food poisoning potential of strains of the new species in the Bacillus cereus group, B. weihenstephanensis. Fifty strains were tested for cytotoxicity in a Vero cell assay, and 23 of the strains were also tested for production of enterotoxin components with commercial antibody kits, and for presence of enterotoxin gene components by polymerase chain reaction (PCR). The majority of the strains (72%) were not cytotoxic, although all of the strains that were tested with PCR and commercial kits had part of at least one of the B. cereus enterotoxins Hbl, Nhe or CytK.

Animals↗
PubMed2006

Mycobacterium abscessus: an emerging rapid-growing potential pathogen.

Mycobacterium abscessus is the most pathogenic and chemotherapy-resistant rapid-growing mycobacterium. It is commonly associated with contaminated traumatic skin wounds and with post-surgical soft tissue infections. It is also one of the mycobacteria that are most often isolated from cystic fibrosis patients. It is essential to differentiate this species from the formerly indistinct "M. chelonae-complex", as chemotherapy is especially difficult in M. abscessussenso strictu. Clarithromycin or azithromycin are the only regular oral antimycobacterial agents with an effect on M. abscessus, and should preferably be supplemented with other drugs since long-term monotherapy may cause resistance. Amikacin is a major parenteral drug against M. abscessus that should also be given in combination with another drug. The recently introduced drug tigecycline may prove to be an important addition to chemotherapy, but has yet to be fully clinically evaluated as an antimycobacterial agent. Surgery can be curative, or at least helpful, in the healing of M. abscessus infection, and if conducted, it should include the removal of all foreign or necrotic material. There is increasing awareness of M. abscessus as an emerging pathogen.

Administration, Oral↗