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 181 records · Page 10Linked to original sources
PubMedDate not supplied

Treatment strategies for daily life silent myocardial ischemia: a correlation with potential pathogenic mechanisms.

Recent investigations of SMI occurring during daily life have advanced our understanding of the pathophysiology of myocardial ischemia. These contributions have directed our attention away from "chest pain" alone and physical exertion as the central provoking factor toward transient myocardial ischemia and its broader triggers and consequences. Transient myocardial ischemic episodes, the majority of which are silent, are found in a subset of patients with any clinical manifestations of CAD (eg, stable angina, unstable angina, myocardial infarction, and sudden death), as well as in those patients with CAD who are and have been totally asymptomatic. These episodes are an independent predictor of increased risk for future cardiac events. Most medical therapy and revascularization therapies have the potential to prevent or relieve these silent episodes; however, we do not yet know which method is superior in reducing SMI episodes or preventing future cardiac events. Furthermore, the benefit of reducing SMI versus the cost and potential morbidity of these chosen therapies is not known. At least three trials are now underway to examine some of these concerns (Table 2). Focus on pain relief alone does not appear to be an adequate approach to alter outcome in patients with CAD and may prove insufficient to control SMI. Until these issues are resolved, we believe a conservative approach to the management of patients with CAD is warranted. Documentation of ischemia (painful or painless) is essential. Three general principles should be kept in mind. First, the presence of detectable ischemia is of central importance. This information should be used in the overall risk assessment of the patient. Second, the level of concern or aggressiveness of treatment should be based on the risk associated with the ischemic abnormalities documented (Table 3). The exercise stress test is the most useful to begin this process. The detection of ischemic-type ST-segment depression, either silent or painful, at a low workload (eg, less than or equal to 120 beats per minute or less than or equal to 6.5 metabolic equivalents [METS]) implies high risk for adverse outcome. Likewise, these ST-segment changes occurring in leads that reflect multiple coronary artery distribution, of greater than 2 mm in magnitude and persisting for greater than 6 minutes, are all markers for high risk. Thallium redistribution defects occurring at low work loads, in multiple areas, associated with increased lung uptake and enlargement of the cardiac pool all imply high risk.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic beta-Antagonists↗
PubMed1989

Isolation and partial characterisation of a potentially pathogenic cysteine proteinase from adult Dictyocaulus viviparus.

Dictyocaulus viviparus adult worms feed on pulmonary tissues and cause significant pathology in the bovine host. In this report, acidic extracts of these organisms were examined for cysteine proteinase activity. A soluble thiol-dependent proteinase with native molecular weight of approximately 25 kDa was isolated and partially purified. This enzyme had maximal activity at acidic pH and showed inhibitor susceptibilities similar to the vertebrate acidic cysteine proteinases. When stored at 4 degrees C, it was stable at pH 5.0 for at least 10 days and at pH 7.0 for at least 24 h. The D. viviparus cysteine proteinase was capable of degrading type I collagen and hemoglobin. It is suggested that this enzyme may be involved in the nutrition of this parasite and/or have the potential to contribute to bronchial pathology in cattle.

Animals↗
PubMed2006

[Pathogenic potential of Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia, the red bacterial complex associated with periodontitis].

Periodontitis are mixed bacterial infections leading to destruction of tooth-supporting tissues, including periodontal ligament and alveolar bone. Among over 500 bacterial species living in the oral cavity, a bacterial complex named "red complex" and made of Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia has been strongly related to advanced periodontal lesions. While periodontopathogenic bacteria are the primary etiologic factor of periodontitis, tissue destruction essentially results from the host immune response to the bacterial challenge. Members of the red complex are Gram negative anaerobic bacteria expressing numerous virulence factors allowing bacteria to colonize the subgingival sites, to disturb the host defense system, to invade and destroy periodontal tissue as well as to promote the immunodestructive host response. This article reviews current knowledge of the pathogenic mechanisms of bacteria of the red complex leading to tissue and alveolar bone destruction observed during periodontitis.

Animals↗
PubMed1973

Potential pathogens in the environment: Klebsiella pneumoniae, a taxonomic and ecological enigma.

A nitrogen-deficient medium and m-Endo agar were employed in the isolation of members of the tribe Klebsielleae from surfaces of vegetables and seeds. With m-Endo agar at an incubation temperature of 37 C, nearly 50% of the vegetables and seven out of seven seed samples yielded organisms which biochemically and serologically were identified as Klebsiella pneumoniae, Viable counts were generally in the range of 10(3) cells per g of vegetable peel or seed. Organisms classified as K. pneumoniae exhibited seven different IMViC patterns, with the --++, ++++, and -+++ patterns most common. Seven of the eleven K. pneumoniae serotypes encountered have previously been isolated from human urinary tract and other infections. Fifty percent of the 40 K. pneumoniae examined exhibited positive acetylene-reducing activity, i.e., they possessed the capability for fixing N(2). Vegetables containing K. pneumoniae may constitute a potential reservoir for human nosocomial genitourinary or other infections.

Acetylene↗
PubMed2003

Asbestos fiber length as related to potential pathogenicity: a critical review.

BACKGROUND: Asbestos inhalation is recognized as an exposure that increases the risk for the development of lung disease. It is unique among dusts in that it is both a carcinogen and capable of inducing extrapulmonary responses such as pleural thickening and fibrosis as well as malignancy. One feature of asbestos suggested as crucial in its pathological activity is its fibrous morphology. Long fibers that have been inhaled are cleared less readily and are thus more persistent in the body. Furthermore certain experimental models link fiber length to levels of risks for development of certain diseases. The present review will survey the data on this subject. METHODS: The review considers experimental models that have been used to assess the response to various lengths of fibers in animal models in addition to data obtained from studies of human materials. The review also emphasizes the importance in defining the method by which a sample is categorized. RESULTS: Data are offered which support the potential for longer fibers as well as shorter fibers to contribute to pathological responses. CONCLUSIONS: The data presented argue that asbestos fibers of all lengths induce pathological responses and that caution should be exerted when attempting to exclude any population of inhaled fibers, based on their length, from being contributors to the potential for development of asbestos-related diseases.

Asbestos↗
PubMed2002

PCR detection of potentially pathogenic aeromonads in raw and cold-smoked freshwater fish.

AIMS: Development of a PCR assay for detection of aeromonads carrying the hlyA and/or aerA genes in fish. METHODS AND RESULTS: The protocol involves an overnight selective enrichment step in tryptic soy broth yeast extract containing 10 microg ml(-1) of ampicillin followed by extraction of DNA and PCR amplification of two haemolysin genes that contribute to the virulence of Aer. hydrophila. This procedure can detect initial populations of 1-10 cfu g(-1) within 24 h in artificially contaminated samples. In naturally contaminated fish, both genes were detected in 13 out of 14 fresh fish lots (aeromonads levels between < 1 and 5.42 log cfu g(-1)) and in 4 out of 16 lots of vacuum-packed cold-smoked fish (aeromonads levels between < 1 and 3.37 log cfu g(-1)). Before enrichment, dominant species were Aer. hydrophila HG1 (aerA+hlyA+), Aer. bestiarum HG2 (aerA+hlyA+) and Aer. caviae HG4 (aerA-hlyA-). After enrichment, Aer. hydrophila HG1 (aerA+hlyA+) was dominant. CONCLUSIONS: Fresh fish and even smoked fish carry hlyA+ and/or aerA+ aeromonads that can be detected by PCR within 24 h. SIGNIFICANCE AND IMPACT OF THE STUDY: The PCR assay described offers considerable potential as a rapid method with specificity, sensitivity and simplicity.

Aeromonas↗
PubMed1994

Potentially pathogenic vibrios associated with mussels from a tropical region on the Atlantic coast of Brazil.

Mussels (Perna perna) harvested on the coast of Ubatuba, in three different stations in the State of São Paulo, Brazil, were examined for Vibrio spp. over a 1 year period. The ranges of most probable number (MPN 100 g-1) were: Vibrio alginolyticus (< 3-24,000), V. parahaemolyticus (< 3-24,000), V. fluvialis (< 3-1100), V. cholerae non-O1 (< 3-23), V. furnissii (< 3-30), V. mimicus (< 3-9) and V. vulnificus (< 3-3). The highest incidence was observed for V. alginolyticus (92-100%), followed by V. parahaemolyticus (67-92%), V. fluvialis (34-67%), V. vulnificus (8-17%), V. furnissii (0-17%), V. mimicus (0-17%) and V. cholerae non-O1 (0-8%). Tests for virulence factors were positive in 34.1% of the vibrios in the rabbit ileal loop and 31.7% in the Dean test. Positive results in the Kanagawa test were obtained with 0.51% of V. parahaemolyticus strains. The mean values (MPN 100 g-1) of faecal coliforms in mussels from the three regions varied from 1100 to 44,000, and seawater collected at the same stations gave average values for faecal coliforms in the range 18-3300 MPN 100 ml-1. These results highlight the potential risks of food poisoning associated with raw or undercooked seafood.

Animals↗
PubMed1996

The immunogenic and pathogenic potential of short poly(C) tract Mengo viruses.

We have shown previously that genetically engineered Mengo viruses with artificial deletions in their 5' noncoding polyribocytidylic acid (poly(C)) tracts are highly attenuated for the natural murine host and also for other animals such as baboons, macaques, and domestic pigs. The present report further characterizes select short poly(C) tract Mengo viruses in the natural murine host. A positive correlation was found between the length of the poly(C) tract and murine virulence, as measured by virus brain titers and brain lesion scores after infection. Histological examination of brain tissue collected from infected animals clearly showed that the short poly(C) tract viruses did not induce the devastating pathological effects characteristic of animals inoculated with wild-type virus. Instead, the short-tract Mengo viruses proved excellent immunological agents. A dose of only 100 plaque-forming units of vMC24 (poly(C) tract: C13UC10), injected subcutaneously, protected 80% of recipient animals against a normally lethal dose of encephalomyocarditis virus. The protection was long-lived, and animals similarly immunized with vMCo virus (poly(C) tract: Co) still had protective neutralizing antibody titers up to 16 months after inoculation. In addition, the short-tract viruses proved genetically stable, in that the vMC24 virus did not yield detectable pathogenic revertants even after multiple, forced passages in 4-week-old mice. These studies suggest that Mengo viruses containing deletions in their poly(C) tracts are biologically safe and potent immunogens and imply that they may have uses as cardiovirus vaccines.

Animals↗
PubMed1998

Activation of human orbital fibroblasts through CD40 engagement results in a dramatic induction of hyaluronan synthesis and prostaglandin endoperoxide H synthase-2 expression. Insights into potential pathogenic mechanisms of thyroid-associated ophthalmopathy.

Human orbital fibroblasts play a putative role in the pathogenesis of thyroid-associated ophthalmopathy (TAO). We hypothesize that the hyaluronan accumulation and inflammation in TAO derive from enhanced biosynthetic activities of orbital fibroblasts. CD40, a member of the tumor necrosis factor-alpha receptor superfamily, is a critical signaling molecule expressed by B lymphocytes. Engagement of CD40 with CD154 or CD40 ligand results in the activation of target genes. Orbital fibroblasts also display CD40. Here we report that CD40 engagement leads to substantial increases in hyaluronan synthesis in orbital fibroblasts. The increase is approximately 5-fold above control values, is comparable to the induction elicited by IL-1beta and could be attenuated with dexamethasone but not by SC 58125, a prostaglandin endoperoxide H synthase-2 (PGHS-2)-selective inhibitor. PGHS-2 is also induced by CD40 engagement in a time-dependent manner, and this is mediated through increases in levels of steady-state mRNA. The induction of PGHS-2 leads to a dramatically enhanced prostaglandin E2 production that can be blocked by SC 58125 and dexamethasone. CD40 ligand up-regulates the synthesis of IL-1alpha, and blocking this cytokine with exogenous IL-1 receptor antagonist (IL-1ra) or with IL-1alpha neutralizing antibodies partially attenuates the induction of PGHS-2. In contrast, CD40 ligand up-regulation of hyaluronan synthesis is unaffected by IL-1ra. CD40 cross-linking enhances mitogen-activated protein kinase activation, and interrupting this pathway attenuates the PGHS-2 induction. Thus the CD40/CD40 ligand bridge represents a potentially important activational pathway for orbital fibroblasts that may underlie the cross-talk between these cells and leukocytes. These findings may be relevant to the pathogenesis of TAO and provide insights into previously unrecognized, potential therapeutic targets.

CD40 Antigens↗
PubMed1999

Human herpesviruses 6 and 7 as potential pathogens after liver transplant: prospective comparison with the effect of cytomegalovirus.

Because cytomegalovirus (CMV) is an important opportunistic infection after liver transplant, we conducted a prospective study to see if the same applied to human herpesviruses (HHV)-6 and -7. We used polymerase chain reaction (PCR) methods optimised to detect active, not latent, infection and studied patients not receiving antiviral prophylaxis for CMV. Post-transplant, 536 blood samples were tested by PCR (median 7; range 4-50). Active infection with CMV was detected in 28/60 (47%), HHV-6 in 19/60 (32%), and HHV-7 in 29/60 (48%) of patients. The PCR-positive samples were tested by quantitative-competitive PCR to measure the virus load of each betaherpesvirus. The median peak virus load for CMV was significantly greater than that for HHV-6 or HHV-7. Detailed clinicopathological analyses for the whole population showed that CMV and HHV-6 were each significantly associated with biopsy-proven graft rejection. Individual case histories suggested that HHV-6 and HHV-7 may be the cause of some episodes of hepatitis and pyrexia. It is concluded that HHV-6 is a previously unrecognized contributor to the morbidity of liver transplantation, that HHV-7 may also be important and that both viruses should be included in the differential diagnosis of graft dysfunction.

Adult↗
PubMed1996

Dysregulation of potentially pathogenic self reactivity is crucial for the manifestation of clinical autoimmunity.

During the evolution of the autoimmune response to myelin basic protein (MBP), at least two distinct lymphocyte populations arise, one that is specific for determinants within the protein antigen and another that is specific for the receptors displayed by the antigen-specific lymphocytes themselves. The T-cell receptor (TCR)-specific lymphocytes appear to oppose the action of the pathogenic effector cells, which predominantly utilize the TCR V beta 8.2 gene segment. We will discuss our work suggesting that both CD4 and CD8 cells specific for different TCR determinants on the V beta 8.2 chain are involved in the regulation of MBP-specific CD4 T cells mediating experimental autoimmune encephalomyelitis. We suggest that a crucial balance between the effectors and regulators is decisive for the clinical manifestation of autoimmunity.

Animals↗
PubMed2001

Caudal dysplasia sequence with penile enlargement: case report and a potential pathogenic hypothesis.

The clinical spectrum of caudal dysplasia sequence (CDS) is noted for its diversity. The origin of CDS remains unknown, though poorly controlled gestational diabetes has been implicated in some cases. Here we describe the case of a newborn with CDS associated with penile enlargement (PE). The main anomalies included anal atresia, agenesis of the kidneys and of the sacrococcygeal vertebrae, dysgenesis of lumbar vertebrae, and bilateral cryptorchidism. Penile enlargement (7 cm), a rather unusual finding, has so far not been reported in association with CDS. Chromosomal analysis failed, and the neonate died 30 min after birth. Comparative genomic hybridization analysis using stored DNA showed a balanced normal male DNA content, which negates chromosomal losses or gains as a cause of CDS and/or PE. PE due to virilizing-type adrenal hyperplasia, caused by common mutations in the genes encoding for the adrenal enzymes 21-hydroxylase and 11-hydroxylase, was ruled out. We report on a previously unpublished case of the coexistence of PE and severe CDS and propose a possible pathogenetic hypothesis of this association.

Abnormalities, Multiple↗
PubMed1984

[Adherence to the gastrointestinal wall and potential pathogenicity of gastrointestinal germs].

Under certain circumstances--invasion of adhesive germs, abundant reproduction of the germs at the mucosa, a lowered resistance of the body--the adhesive flora can become a pathogenic factor itself. All hitherto known researchers point out that, in this connection, adhesions at the small intestinal wall is of main importance, as could be shown by our experiment with gnotobiotic rats, too. From the results of our experiments regarding the adhesion mechanisms, we conclude that the possibilities of prophylaxis and therapy of gastrointestinal disturbances induced by microbial effects could be extended by means of aimed inhibition of such adhesion forces.

Adhesiveness↗
PubMed2002

A review of potential pathogens of sea lice and the application of cleaner fish in biological control.

There are many examples of successful biological control of pest populations in aquatic environments. This approach to sea louse control has environmental benefits and is cost-effective. The range of possible pathogens of lice is reviewed and epibionts recorded from sea lice, including the monogenean Udonella caligorum and ciliates, are examined. Baculoviruses when ingested by insects form occlusion bodies resulting in severe damage to the digestive system and subsequent death, and this may be a promising approach. Cleaner wrasse (Labridae) have been stocked commercially with farmed salmon since 1989, and recent work on improving the method is reviewed. Wrasse are sourced from a wild fishery and stocked at ratios of 1 to 25-150 salmon. Over 5 million wrasse are stocked annually in Norway and c 30% of smolts in Scotland were stocked with wrasse until 1998, when an outbreak of infections salmon anaemia (ISA) deterred many farmers from transferring wild fish to cages. A case study is given showing that salmon in cages stocked with wrasse had a burden of one to eight lice through the first year compared with up to 40 lice per fish on unprotected and untreated fish. Electivity indices were used to compare the relative composition of lice developmental stages on salmon in stocked and unstocked cages, and adult male and female lice were found to comprise only 6% of the population in cages with wrasse, compared with 49% adults on fish in control cages. Measures to improve the efficacy of wrasse as a way of cleaning salmon in the second production year include the use of refuges to assist over-wintering survival, and stocking ballan wrasse. Health hygiene includes sourcing wrasse in the farm locality, testing for pathogens, vaccination of wrasse and ultimately rearing wrasse for stocking. The role of wrasse in an IPM strategy is described.

Animals↗
PubMed1997

Specific detection of Serpulina hyodysenteriae and potentially pathogenic weakly beta-haemolytic porcine intestinal spirochetes by polymerase chain reaction targeting 23S rDNA.

A 2470-bp section of the 23S ribosomal DNA from Serpulina hyodysenteriae and five biochemically different groups of weakly beta-haemolytic porcine intestinal Serpulina strains was sequenced. The similarity between the sequenced strains was high (96.85% to 99.84%). A phylogenetic tree was estimated by the maximum likelihood method. The sequenced strains formed three groups. Serpulina hyodysenteriae and biochemical group II ('S. intermedius') formed a cluster, but 20 nucleotide positions were different between the two, suggesting that biochemical group II is a separate species. Another cluster consisted of the closely related biochemical group IIIa ('S. murdochii') and IIIb/c (S. innocens) (99.84% similarity), while biochemical group IV (S. pilosicoli) constituted a separate group with a relatively low similarity (96.85% to 97.01%) to the other groups. Three primer pairs were designed for specific PCR detection of the clinically important S. hyodysenteriae and biochemical group II and IV. PCR amplification was accomplished with DNA extracted from bacterial colonies by a simple boiling procedure, and with DNA extracted directly from porcine stool samples using a bead beating extraction procedure. The level of detection for the direct extraction and amplification method was 5 x 10(5) cells added g-1 normal faeces.

Animals↗
PubMed1993

Pathogenic potential of myeloblastosis-associated virus: implication of env proteins for osteopetrosis induction.

To identify the nucleotide sequences responsible for the tumorigenic specificity of myeloblastosis-associated virus (MAV) we have established the complete nucleotide sequences of three infectious clones inducing either both osteopetrosis and nephroblastoma [MAV2(O)/2 and MAV2(O)p9] or only nephroblastoma [MAV1(N)], and compared their biological properties in the same chicken host strain. The MAV2(O)p9 originally described as a type 2 strain was found to carry a hybrid env gene containing sequences of both the types 1 and 2, and it induced milder and less rapid osteopetrosis than the original MAV2(O) clone when injected into Brown Leghorn chickens. These results, together with sequence comparisons between the MAV strains examined, suggest that subtle changes in the primary structure of the TM env protein's extracellular domain are likely to affect the tumorigenic potential of MAV.

Amino Acid Sequence↗