Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Potential pathogens”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,423 records · Page 79Linked to original sources
PubMed2006

Structural congruence among membrane-active host defense polypeptides of diverse phylogeny.

A requisite for efficacious host defense against pathogens and predators has prioritized evolution of effector molecules thereof. A recent multidimensional analysis of physicochemical properties revealed a novel, unifying structural signature among virtually all classes of cysteine-containing antimicrobial peptides. This motif, termed the gamma-core, is seen in host defense peptides from organisms spanning more than 2.6 billion years of evolution. Interestingly, many toxins possess the gamma-core signature, consistent with discoveries of their direct antimicrobial activity. Many microbicidal chemokines (kinocidins) likewise contain iterations of the gamma-core motif, reconciling their antimicrobial efficacy. Importantly, these polypeptide classes have evolved to target and modulate biomembranes in protecting respective hosts against unfavorable interactions with potential pathogens or predators. Extending on this concept, the current report addresses the hypothesis that antimicrobial peptides, kinocidins, and polypeptide toxins are structurally congruent and share a remarkably close phylogenetic relationship, paralleling their roles in host-pathogen relationships. Analyses of their mature amino acid sequences demonstrated that cysteine-stabilized antimicrobial peptides, kinocidins, and toxins share ancient evolutionary relatedness stemming from early precursors of the gamma-core signature. Moreover, comparative 3-D structure analysis revealed recurring iterations of antimicrobial peptide gamma-core motifs within kinocidins and toxins. However, despite such congruence in gamma-core motifs, the kinocidins diverged in overall homology from microbicidal peptides or toxins. These findings are consistent with observations that chemokines are not toxic to mammalian cells, in contrast to many antimicrobial peptides and toxins. Thus, specific functions of these molecular effectors may be governed by specific configurations of structural modules associated with a common gamma-core motif. These concepts are consistent with the hypothesis that the gamma-core is an archetype determinant in polypeptides that target or regulate with biological membranes, with specific iterations optimized to unique or cognate host defense contexts. Quantitative and qualitative data suggest these protein families emerged through both parallel and divergent processes of modular evolution. Taken together, the current and prior findings imply that the gamma-core motif contributes to conserved structures and functions of host defense polypeptides. The presence of this unifying molecular signature in otherwise diverse categories of membrane-active host defense peptides implies an ancient and essential role for such a motif in effector molecules governing host-pathogen relationships.

Amino Acid Sequence↗
PubMed1993

Resistance to nitric oxide in Mycobacterium avium complex and its implication in pathogenesis.

Susceptibility of three different strains of Mycobacterium avium complex (MAC), i.e., one strain of M. avium (Mino) and two strains of M. intracellulare (31F093T and KUMS 9007), to nitric oxide (NO) generated by rat alveolar macrophages (M phi) or NO generated chemically by acidification of NO2- was examined in vitro. We also investigated the effects of NO on phagocytosis and superoxide anion (O2-) generation by M phi. The intracellular growth of M. avium Mino was significantly suppressed by NO generated by gamma interferon (IFN-gamma)-stimulated M phi, whereas that of two strains of M. intracellulare (31F093T and KUMS 9007) was not. M. avium Mino was also more susceptible to NO generated chemically by acidification of NO2- than the two M. intracellulare strains. In L-arginine (1 mM)-containing medium, NO release from the M phi assessed by measuring NO2- increased as the concentration of IFN-gamma increased. The enhancing potential of IFN-gamma for NO release became more pronounced when M phi were infected with 31F093T, an NO-resistant strain. A large amount of NO generated by IFN-gamma-stimulated M phi suppressed both phagocytosis and O2- generation by the M phi, especially after infection of the M phi with strain 31F093T. These results indicate that the intracellular growth of MAC is not always inhibited by NO generated by immunologically activated M phi; rather, NO generation induced by infection with an NO-resistant MAC strain suppresses phagocytosis of the M phi, which may allow extracellular spreading of such NO-resistant mycobacteria. Therefore, the pathogenic potential of MAC may be partly attributed to its resistance to NO.

Animals↗
PubMed2000

Role of genetic factors in organ-specific autoimmune diseases induced by manipulating the thymus or T cells, and not self-antigens.

There are accumulating demonstrations that manipulation of the T-cell immune system, such as elimination of a particular T-cell subpopulation from the periphery or removal of the thymus during a critical neonatal period, can elicit activation/expansion of pathogenic self-reactive T cells from the remaining T cells and produce a wide spectrum of organ-specific autoimmune diseases in otherwise normal mice or rats. The genetic makeup of the hosts appears to play a key role in determining which self-reactive T-cell clones are prone to be activated under such circumstances, since a comparable degree of the immunologic abnormality elicits autoimmune disease in different spectrums of organs, with different incidences and severities, depending on the mouse or rat strains used. These findings indicate that one aspect of natural immunologic self-tolerance is maintained by a T cell-mediated control of potentially pathogenic self-reactive T cells in the periphery, and that defective control, caused by environmental insults or genetic abnormalities, suffices to cause autoimmune disease; furthermore, in the presence of such a T-cell abnormality, host genetic factors including MHC and non-MHC genes may determine the specificity and intensity of the autoimmune responses, and consequently the phenotype of the autoimmune disease.

Animals↗
PubMed1997

Development of a highly specific assay for rapid identification of pathogenic strains of Yersinia enterocolitica based on PCR amplification of the Yersinia heat-stable enterotoxin gene (yst).

The chromosomal gene yst, which encodes a heat-stable enterotoxin of Yersinia enterocolitica, is a useful diagnostic marker because it occurs only in invasive strains of this species. A homologous gene also occurs in some strains of Yersinia kristensenii. Sequence analysis of the yst genes from two different strains of Y. enterocolitica and from Y. kristensenii revealed a substantial number of mismatches at the 3' ends of the yst genes of the so-called American and European biotypes of Y. enterocolitica. Moreover, several mismatches and a deletion of 5 codons were found in the yst of Y. kristensenii. These findings were used to develop a PCR-based assay for yst of Y. enterocolitica which yielded a detectable product in as little as 50 min. The assay was 100% specific in terms of its ability to identify potentially pathogenic strains of Y. enterocolitica regardless of biotype or serotype. The PCR yielded an amplicon that was visible on agarose gel electrophoresis from as few as 100 CFU, or 10 CFU when the PCR was combined with dot blot hybridization with a digoxigenin-labeled oligonucleotide probe that corresponded to an internal sequence of yst. These results establish the value of the yst gene as a target for the identification of pathogenic bioserotypes of Y. enterocolitica and the usefulness of PCR for this purpose.

Amino Acid Sequence↗
PubMed1999

Autoimmune myocarditis does not require B cells for antigen presentation.

T cells constitute the pathogenic effector cell population in autoimmune myocarditis in BALB/c mice. Using mice rendered deficient for B cells by a targeted disruption to the IgM transmembrane domain or by treatment with anti-IgM Ab from birth, we asked whether B cells are a critical APC in the induction of autoimmune myocarditis. B cell-deficient mice immunized with cardiac myosin develop myocarditis comparable in incidence and severity to that in wild-type mice, suggesting that autoreactive T cells that cause myocarditis in BALB/c mice are activated by macrophages or dendritic cells. Since it does not appear that presentation of cryptic epitopes is critical for the breakdown of self tolerance, potentially pathogenic T cells recognizing dominant myosin epitopes must have escaped tolerization. Either anatomic sequestration of cardiac myosin peptide-MHC complexes or subthreshold presentation of cardiac myosin peptides by conventional APC can explain the survival of these autoreactive T cells.

Animals↗
PubMed1992

Human foamy virus: an underestimated neuropathogen?

Human foamy virus (HFV) is a recently characterized retrovirus which was originally isolated from patients with various neoplastic and degenerative diseases. However, until today it has not been possible to identify HFV as the causative agent of any disease and little is known about its prevalence in human populations. Like HTLV and HIV, HFV encodes the three structural retroviral genes, gag, pol and env, and an additional region containing three open reading frames, bel-1 to bel-3. Bel-1 activates transcription of the long terminal repeat of HFV and HIV. In order to study the consequences of expressing HFV regulatory genes and to investigate a possible pathogenic potential of HFV, we have introduced parts of the HFV genome into the germ line of mice. Our studies with transgenic mice demonstrate that HFV transgenes encompassing the bel region are transiently transcribed between midgestation and birth at moderate levels in various tissues. Expression is then suppressed, but resumes after a latency of several weeks in a restricted range of tissues and leads to extensive accumulation of HFV transcripts in single cells. This is associated with a progressive degenerative disease of the central nervous system and of striated muscle. These findings provide the first evidence of a disease induced by HFV and suggest that HFV might also act as a human pathogen in neurological diseases. Moreover, the transgenic mouse model will be useful for studying the molecular basis of HFV-induced neurotoxicity, the role of individual disease-associated HFV genes and the regulation of retroviral latency.

Animals↗
PubMed1986

Consequences of treatment of gastrointestinal infections.

Diarrhoeal disease is a common problem in developing countries. As a result of recent advances in diagnostic methodology, the causative agents can now be identified in most cases of acute diarrhoeal diseases. Enteric bacterial pathogens are the common cause of gastroenteritis in developing countries. Appropriate uses of antibiotics in selected cases of diarrhoea will decrease symptoms or reduce faecal shedding of the organism and prevent spread of infection. Antimicrobial agents improve the diarrhoea associated with cholera, shigellosis, enteric fever, enterotoxigenic Escherichia coli, giardiasis, amoebiasis, and probably Vibrio parahaemolyticus, and enteropathogenic E. coli. Antibiotics have no role in the treatment of viral diarrhoea or uncomplicated salmonella gastroenteritis. Most of the diarrhoeal diseases are self-limited and the wrong choice of antimicrobial agents will worsen the symptoms. Treatment of gastrointestinal infections with antimicrobials will change intestinal microflora, promote the emergence of resistant strains and overgrowth of potential pathogenic bacteria and fungi. Risks and benefits should be considered before prescribing antimicrobial agents.

Anti-Bacterial Agents↗
PubMed2003

Pathogenic colonization of oral flora in frail elderly patients fed by nasogastric tube or percutaneous enterogastric tube.

BACKGROUND: Aspiration of infected oropharyngeal content is the main cause of aspiration pneumonia. This complication, mainly related to gram-negative bacteria, threatens percutaneous enterogastric tube as well as nasogastric tube (NGT) fed patients. The objective of this study was to examine the oral microbiota of tuboenterally fed patients and compare it with that of orally fed counterparts. METHODS: Patients were recruited for this study from six nursing and skilled nursing facilities with an overall number of 845 beds. Enrolled were 215 patients: Group 1 consisted of 78 patients on NGT feeding, Group 2 consisted of 57 patients on percutaneous enterogastric tube feeding, and Group 3 consisted of 80 patients fed orally who were from the same facilities. Cultures were performed by sampling the oropharynx of each subject in order to identify gram-negative bacteria and Staphylococcus aureus. RESULTS: A high prevalence of potentially pathogenic isolations was found in tuboenterally fed patients: 81% in Group 1 and 51% in Group 2, as compared with only 17.5% in Group 3 (p <.0001). Pseudomonas aeruginosa was cultured from 31% of the subjects in Group 1 and 10% of Group 2, but in none of Group 3 (p <.001). Klebsiella and Proteus were isolated mainly from the NGT fed patients (p <.003). No correlation was found between the time duration on tube feeding or the presence of residual dentition and pathogenic microbiota. CONCLUSION: This study shows that tuboenteral feeding in elderly patients is associated with pathogenic colonization of the oropharynx. These findings are related to the risk of aspiration pneumonia and are compelling for the reevaluation of current oral cleansing procedures.

Aged↗
PubMed1986

Virulence mechanisms associated with clinical isolates of non-O1 Vibrio cholerae.

Twenty one isolates of non-O1 V. cholerae from patients with diarrheal illness were examined for the presence of potential virulence mechanisms. The motile strains (90%) produced cell-associated mannose-sensitive hemagglutinins which reacted with human group O, chicken, sheep and rabbit erythrocytes. Motile isolates also attached to embryonic intestinal epithelial cells (ATCC 407), and the adherence was not inhibited by the presence of 1% D-mannose. All vibrio isolates hemolyzed sheep erythrocytes. Three vibrio isolates (14%) harbored two or three plasmids which ranged in size between 1.7 and 5.2 megadaltons. The presence of the plasmid did not correlate with the presence of hemolysin, hemagglutinins, adhesions or antibiotic resistance in any of the isolates. Thus, it appears that multiple factors associated with bacterial cell surfaces influence adhesin and apparently pathogenic potential of the non-O1 vibrio isolates in the host intestine.

Adhesiveness↗
PubMed1997

Comparison of inducible nitric oxide synthase gene expression and lung inflammation following intratracheal instillation of silica, coal, carbonyl iron, or titanium dioxide in rats.

The pulmonary toxicity of the respirable dusts silica, coal, carbonyl iron, and titanium dioxide on alveolar macrophage (AM) and neutrophil (PMN) inducible nitric oxide synthase (iNOS) gene expression and nitric oxide (NO) production was investigated. Rats were intratracheally instilled with 5 mg/100 g body weight of silica, coal, carbonyl iron, or titanium dioxide. The dust particles averaged less than 5 microns in diameter. Bronchoalveolar lavage was performed 24 h later. Bronchoalveolar lavage cell (BALC) differentials, iNOS gene expression and NO production by BALC (measured indirectly as NO-dependent chemiluminescence), and lavageable lung protein levels were measured. Analyzed on an equal mass basis, silica, coal, and titanium dioxide dusts increased the production of iNOS-dependent NO by AM. Silica and titanium dioxide both increased the levels of iNOS mRNA while carbonyl iron and coal did not. Each dust caused an increase in PMN, indicating an inflammatory response. Carbonyl iron and titanium dioxide decreased the numbers of AM. Levels of acellular lavageable lung protein were increased by silica, carbonyl iron, and titanium dioxide. When exposure was normalized for an equal number of particles, the pneumotoxic dusts, silica and coal, caused more inflammation and NO production than the nuisance dusts, carbonyl iron and titanium dioxide. Therefore, it appears that particle number is a more appropriate metric of exposure than mass when comparing the relative pathogenicity of dusts of different sizes. Furthermore, since the potency of these dusts (on a particle number basis) to increase iNOS gene expression reflects their inflammatory and pathogenic potential, it is proposed that NO may contribute to the early inflammatory damage observed in the lung following dust exposure.

Air Pollutants↗
PubMed1991

Sensitivity and specificity of daily tracheal aspirate cultures in predicting organisms causing bacteremia in ventilated neonates.

The sensitivity of daily tracheal aspirates in predicting neonatal bacteremia was ascertained from 48 of 354 ventilated neonates who became septic during a 4-year period. Fourteen babies (designated Group A) had a positive blood culture on the first day of life; 28 infants (Group B) and 6 infants (Group C) had bacteremia beyond the first day. Group C infants became septic as a result of intraabdominal pathology. Pathogens isolated from blood were correlated with those from preceding daily tracheal aspirates. The overall sensitivity of tracheal cultures in predicting results of blood cultures was 81% (Group A, 71%; Group B, 93%; Group C, 50%). The specificity of daily tracheal aspirates was ascertained from 28 of 50 ventilated infants who were nonseptic and had negative blood cultures during a 6-month period. Only 18 had consistently sterile tracheal aspirates (specificity, 64%). The mean number of days of intubation was 6.6 for the 10 false positive and 3.6 for the 18 true negative. Because of low positive predictive value (0.26) the role of daily tracheal aspirate culture is limited to providing early information regarding potential pathogens when sepsis occurs rather than to identify babies who are going to become septic.

Escherichia coli↗
PubMed2004

Toll-like receptor (TLR) expression and TLR-mediated cytokine/chemokine production by human uterine epithelial cells.

The objective of this study was to examine the expression of toll-like receptors (TLRs) by the uterine epithelial cell line ECC-1 and to determine if stimulation of the expressed TLRs induces changes in cytokine and/or chemokine secretion. The expression of TLR1 to TLR9 by ECC-1 cells was demonstrated by reverse transcription polymerase chain reaction, with only TLR10 not being expressed. Stimulation of ECC-1 cells using agonists to TLR2, TLR4 and TLR5 induced the expression of the chemokines interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1), as well as the pro-inflammatory cytokine IL-6, and occurred in a dose-dependent manner. In response to zymosan and flagellin, pathogen-associated molecular patterns (PAMP) that are recognized by TLR2 and TLR5 respectively, ECC-1 cells secreted significantly more IL-8, MCP-1 and IL-6 than in response to other TLR agonists. In contrast, agonists to TLR3, TLR7, and TLR9 had no effect on the secretion of the 13 cytokines or chemokines analysed. These results indicate that uterine epithelial cells are important sentinels of the innate immune system. Further it indicates that all but one of the known TLRs are expressed by ECC-1 cells and that stimulation through specific TLRs mediates changes in the expression of key chemokines and pro-inflammatory cytokines that aid in the defence of the uterus against potential pathogens.

Analysis of Variance↗
PubMed1982

Oral effect of other carbohydrates.

Historical data, epidemiological surveys, laboratory and animal experiments, clinical studies and observations in ordinary dental practice all illustrate that starchy fibrous foods have a low cariogenic potential. The recommended substitution of sucrose in Western diets by starchy foods would lead to a reduction of caries provided that these other carbohydrates replace the between meal consumption of sugar-rich products. The low cariogenic potential of a diet containing carbohydrates with a fibrous character is probably not solely due to its low sucrose content. Such a diet promotes mastication and saliva secretion which tend to reduce the caries risk. Furthermore, unrefined foods may contain caries-protective substances like phytates, trace elements and antibacterial factors. Lectins, which are found in many plants could be of importance by influencing the attachment of micro-organisms to the teeth in a favourable manner. The tradition to end a meal with fruit may thus have other oral effects than hitherto considered. In addition, a diet containing carbohydrates with a fibrous character and a low amount of sucrose probably has a low pathogenic potential for the periodontal tissues. However, no epidemiological data are available to support this assumption.

Animals↗
PubMed1987

Candida osteomyelitis. Report of five cases and review of the literature.

Candida species have emerged as important pathogens in human infection. Although a variety of deep-seated candidal infections have been reported, Candida osteomyelitis has rarely been described. Five patients with Candida osteomyelitis are presented, and the 32 adult cases previously reported are reviewed. Candida osteomyelitis is noted as a simultaneous occurrence or late manifestation of hematogenously disseminated candidiasis. Osteomyelitis may not be prevented by a course of amphotericin B adequate to control the acute episode of disseminated candidiasis, particularly in immunosuppressed patients. Less commonly, Candida osteomyelitis presents as a postoperative wound infection. Like bacterial osteomyelitis, the most common presenting symptom is local pain. The insidious progression of infection, the nonspecificity of laboratory data, and the failure to recognize Candida as a potential pathogen may lead to diagnostic delay. Diagnosis can be made by either open biopsy or closed needle aspiration. Successful therapeutic regimens have employed combinations of antifungal therapy (most often amphotericin B) with surgical debridement when indicated. It is anticipated that osteomyelitis will become a more commonly recognized manifestation of hematogenously disseminated candidiasis.

Aged↗
PubMed1997

[Serological investigation on Yang Xiao-xia's "mysterious disease"].

The famous "mysterious disease" of Yang Xiao-xia, a girl from Shangdong Province, was diagnosed as multi-bacterial synergistic gangrene based on bacteriological, serological and antibiotics sensitivity findings. In order to uncover the initial pathogenic bacteria and to investigate their relationship with environment, a total number of 18 serum samples were collected from volunteers living around patient's home and from patient's relatives. Serological study on 4 bacterial strains isolated from patient, named as Eubacterim lentum, Stereptococcus acidominimus, Y6 and Yp was conducted with Western blot, using whole cell protein preparation was carried out, and data obtained was statistically analysed. Our findings indicated that YP and Y6 strains were interrelated with environment of patient's home and Y6 from the pool where patient visited often and several hours before she intially experienced the disease. The strains of Y6 and YP are virulent to animials, indicating that they serve as potential pathogens. Eubacteriumlentum and Streptococcus acidominimus are irrelevant to environment.

Bacterial Infections↗
PubMed1993

Enteral feeding of premature infants with Lactobacillus GG.

The objectives of this study were to determine whether or not the probiotic Lactobacillus GG can colonise the immature bowel of premature infants and if so, does colonisation result in a reduction of the size of the bowel reservoir of nosocomial pathogens such as enterobacteriaceae, enterococci, yeasts or staphylococci, and does colonisation with Lactobacillus GG have any effect on the clinical progress and outcome. Twenty preterm infants with a gestational age of 33 weeks or less who were resident on a neonatal unit were studied from the initiation of milk feeds until discharge. The infants were randomised to receive either milk feeds or milk feeds supplemented with Lactobacillus GG 10(8) colony forming units twice a day for two weeks. The clinical features of the two groups of infants were similar. Orally administered Lactobacillus GG was well tolerated and did colonise the bowel of premature infants. However, colonisation with Lactobacillus GG did not reduce the faecal reservoir of potential pathogens and there was no evidence that colonisation had any positive clinical benefit for this particular group of infants.

Bacteria, Anaerobic↗
PubMed2000

Clues to the presence of pathogenic fungi in certain environments.

The presence of various pathogenic fungi in rather unsuspected hosts and environments has always attracted the attention of the scientific community. Reports on the putative role of animals in fungal infections of humans bear important consequences on public health as well as on the understanding of fungal ecology. Fungi are ubiquitous in nature and their great capacity for adaptation allows them to survive and indeed, to thrive, in plants, trees and other natural substrata. Nonetheless, we are just beginning to learn the significance that these diverse fungal habitats have on the increasing number of immunosuppressed individuals. The accidental or permanent presence of fungi in animals, plants, soils and watercourses should not be taken too lightly because they constitute the source where potential pathogens will be contracted. If those fungal habitats that carry the largest risks of exposure could be defined, if seasonal variations in the production of infectious propagules could be determined, and if their mode of transmission were to be assessed, it would be possible to develop protective measures in order to avoid human infection. Additionally, unsuspected avenues for the exploration of fungal survival strategies would be opened, thus enhancing our capacity to react properly to their advancing limits. This paper explores several ecological connections between human pathogenic fungi and certain animals, trees, waterways and degraded organic materials. The occurrence of such connections in highly endemic areas will hopefully furnish more precise clues to fungal habitats and allow the design of control programs aimed at avoiding human infection.

Animals↗
PubMed1996

Inflammatory and immunological nature of atherosclerosis.

Recent studies have revealed that atherosclerosis bears several similarities to chronic inflammation. One of the earliest events in both human and experimental atherosclerosis is adhesion of monocytes and T lymphocytes to endothelial surface followed by their migration into the intima. This intimal recruitment of blood derived cells, coupled with the enhanced endothelial permeability to plasma proteins, indicates a potential role for inflammatory mechanisms in early atherogenesis. Colocalization of T lymphocytes and macrophages in all stages of human atherosclerosis, from grossly normal prelesional intima to fully advanced atheromatous plaques, and expression of cytokines and MHC class II antigens by many types of cells of the lesion provide further evidence that atherosclerosis has both the inflammatory and immune nature. The presence of T lymphocytes and macrophages in pairs with a close contact to each other suggests that cognate cell to cell interaction also plays a pivotal role in the pathogenesis of atherosclerosis. It seems conceivable that the T lymphocyte-macrophage interaction particularly takes place in the areas where atherosclerotic lesions are in progress or being active. The pathogenic potentials of immunologic factors are fruitful subjects for further investigation.

Animals↗