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At least 199 records · Page 11Linked to original sources
PubMed1994

Emergence of a potentially pathogenic H5N2 influenza virus in chickens.

Highly pathogenic influenza A viruses periodically infect both humans and nonhuman animals, including chickens. To gain insight into the origin of influenza outbreaks in poultry, we investigated two H5N2 viruses, A/chicken/Pennsylvania/13609/93 (Ck/PA/93) and A/chicken/Florida/25717/93 (Ck/FLA/93), that had been isolated in live-bird markets in Pennsylvania and Florida during surveillance studies in 1993. Phylogenetic analysis of the HA genes of these isolates, as well as H5N2 viruses isolated from ruddy turnstone surfbirds in 1991 (A/ruddy turnstone/Delaware/244/91 [RT/DE/91]) and other known H5 strains, indicated that Ck/PA/93 and Ck/FLA/93 share a common ancestor with RT/DE/91 and did not originate from A/chicken/Pennsylvania/1370/83 (Ck/PA/1370/83), which devastated chicken populations in 1983-1984. Both isolates were nonpathogenic in chickens by experimental infection and their HA protein (HA0) could not be cleaved into HA1 and HA2 without trypsin. The sequences at the HA cleavage sites of Ck/PA/93 and Ck/FLA/93 (R-K-T-R) appear to be intermediate between those of virulent and avirulent viruses, raising the possibility that a single mutation could promote virulence in chickens. We therefore recommend eradication of such viruses as soon as they appear.

Amino Acid Sequence↗
PubMed1993

Biology and neurobiology of Borna disease viruses (BDV), defined by antibodies, neutralizability and their pathogenic potential.

Borna disease viruses (BDV) isolated from more than 20 naturally infected horses, 2 sheep and a possible feline isolate were included in these studies. Most of these wild-type viruses were grown in rabbit cells. Specifically rabbit-adapted viruses establish persistent infection in immortalized cell lines of various animal species. Brain-, tissue culture-, and cell-free released viruses could all be neutralized with antibodies from naturally and experimentally infected animals (horse; hamster, rat, rabbit, mouse, and chicken), with highest titres in birds. Splenectomized rabbits, which were subsequently infected with BDV, efficiently produced high titres of neutralizing antibodies. All of the neutralizing sera and cerebrospinal fluids from infected animals inhibited tissue culture spread of BDV. Experimental infection and hyperimmunization induced antibodies directed against the major components of the soluble antigen (60, 40/38, 25 and 14.5 kD proteins). Analysis of the s-antigen complex with these sera and 6 stable monoclonal antibodies revealed that it consists of 40/38 and 25 kD proteins. Although each of these antibodies detected intracellular virus-specific structures they did not recognize outer plasma membrane antigens, showed no cross-reactivity, and had no neutralizing capacity. Unifying pathogenetic concepts of this neurotropic virus and its structural elements are discussed.

Animals↗
PubMed1993

Myocardial infarction in young patients with Hodgkin's disease--potential pathogenic role of radiotherapy, chemotherapy, and splenectomy.

Among a total of 2147 patients admitted to our hospital for acute myocardial infarction between 1978 and 1987, three young patients aged 24, 29, and 39 years had previously been treated for Hodgkin's disease. Staging laparotomy, including splenectomy, had been performed in all three patients. Two patients had both mediastinal irradiation (21 and 27 months before infarction) and chemotherapy. In the first patient, postmortem histologic examination of the coronary arteries revealed fibrotic changes, which were probably induced by radiotherapy. In our second patient, myocardial infarction developed 5 days after vinblastine treatment; early angiography showed thrombotic occlusion of the proximal right coronary artery, which was recanalized using the diagnostic Sones catheter. Subsequent angiography revealed normal coronary arteries. This is, to our knowledge, the first case of documented coronary artery thrombosis after treatment with vinca-alkaloids. In our third patient, neither mediastinal irradiation nor chemotherapy had been performed prior to myocardial infarction. However, a marked increase in platelet counts following splenectomy was observed in this patient. The role of radiotherapy, chemotherapy, and splenectomy with consecutive thrombocytosis as a third possible pathogenic factor for subsequent development of myocardial infarction is discussed.

Adult↗
PubMed1995

Acute otitis media in children: a study of nasopharyngeal carriage of potential pathogens and therapeutic efficacy of cefixime and amoxicillin-clavulanate.

We conducted a large, multicenter, randomized, open-label study throughout France comparing the efficacy and safety of cefixime suspension (8 mg/kg/day, b.i.d., for 10 days) versus amoxicillin-clavulanate suspension (80 mg/kg/day, t.i.d., for 10 days) in 510 children (ages 6 to 36 months) with acute otitis media. The most frequent microorganisms colonizing the nasopharynx at the start of treatment were Streptococcus pneumoniae (51.5%), Haemophilus influenzae (45%) and Moraxella catarrhalis (30.2%). Rates of beta-lactamase positivity were 32.1% and 95.3% for H. influenzae and M. catarrhalis, respectively. Decreased susceptibility of S. pneumoniae to penicillin was found in 39.7% of isolates. Clinical efficacy was 87.8% (223/254) for cefixime and 87.0% (215/247) for amoxicillin-clavulanate. At the 5-week follow-up visit, relapse had occurred in 15.7% (31/197) of cefixime-treated patients and in 15.6% (32/205) of those treated with amoxicillin-clavulanate. We conclude that these two regimens are equally effective in acute otitis media in children.

Acute Disease↗
PubMed1997

Association of hemorrhoidal disease with diarrheal disorders: potential pathogenic relationship?

UNLABELLED: Despite frequent occurrence of hemorrhoidal disease, its etiology remains controversial. Recent evidence suggests that diarrhea may represent a pathogenic risk factor. The present study examined prevalence of diarrheal disorders in elderly patients with hemorrhoidal disease to provide further insight into its pathogenic mechanisms. METHODS: Using 8.8 million Medicare patients hospitalized in the United States during 1987, the frequency distribution of all three-digit International Classification of Diseases codes was compared in patients with and without hemorrhoidal disease. A more frequent occurrence of a specific disorder in patients with hemorrhoidal disease compared with the general Medicare population suggests that this disorder may be pathophysiologically related or share common etiologic risk factors with hemorrhoidal disease. RESULTS: Strong associations were observed between hemorrhoidal disease and a number of diarrheal disorders, including ulcerative colitis, noninfectious gastroenteritis, and functional diarrhea. Hemorrhoidal disease was likewise closely associated with benign and malignant anorectal neoplasms. CONCLUSIONS: Results of this study must be interpreted with caution because epidemiologic studies cannot establish cause and effect relationships. Nevertheless, these data would seem to further support the pathogenic influence of diarrhea in development of hemorrhoidal disease.

Aged↗
PubMed2005

1-Aryl-5-benzylsulfanyltetrazoles, a new group of antimycobacterial compounds against potentially pathogenic strains.

A set of 21 1-phenyl-5-benzylsulfanyltetrazoles substituted on the phenyl ring as well as on the benzyl moiety was evaluated for in vitro antimycobacterial activity against Mycobacterium avium and two strains of M. kansasii. We tried to use the Hansch approach, the Free-Wilson approach and their combination for structure-activity correlation but the calculations were statistically insignificant.

Anti-Bacterial Agents↗
PubMed2005

Antifungal susceptibility and pathogenic potential of environmental isolated filamentous fungi compared with colonizing agents in immunocompromised patients.

Infection is a major cause of morbidity and mortality in bone marrow transplant recipients and in patients with hematological malignancies. The source of infection is almost always endogenous flora or the hospital environment. The present study evaluated bone marrow transplant recipients and patients with hematological malignancies colonized and/or infected with filamentous fungi. During 1 year, environmental air samples were also taken from the bone marrow transplant unit by a modification of gravity air-setting plate (GASP) methodology. Fusarium spp. were the most prevalent genus in the fall and Cladosporium spp. in the winter. Clinically isolated strains grew better at 37 degrees C than environmental strains. According to NCCLS M-38P methods, environmental Aspergillus strains showed higher MICs to miconazol and itraconazol, and clinical Fusarium strains were less susceptible to fluconazole.

Air Microbiology↗
PubMed2006

Tetrahydrobiopterin availability in Parkinson's and Alzheimer's disease; potential pathogenic mechanisms.

Within the central nervous system, tetrahydrobiopterin (BH4) is an essential cofactor for dopamine and serotonin synthesis. In addition, BH4 is now established to be an essential cofactor for all isoforms of nitric oxide synthase (NOS). Inborn errors of metabolism affecting BH4 availability are well documented and the clinical presentation can be attributed to a paucity of dopamine, serotonin, and nitric oxide (NO) generation. In this article, we have focussed upon the sensitivity of BH4 to oxidative catabolism and the observation that when BH4 is limiting some cellular sources of NOS may generate superoxide whilst other BH4 saturated NOS enzymes may be generating NO. Such a scenario could favor peroxynitrite generation. If peroxynitrite is not scavenged, e.g., by antioxidants such as reduced glutathione, irreversible damage to critical cellular enzymes could ensue. Such targets include components of the mitochondrial electron transport chain, alpha ketoglutarate dehydrogenase and possibly pyruvate dehydrogenase. Such a cascade of events is hypothesized, in this article, to occur in neurodegenerative conditions such as Parkinson's and Alzheimer's disease.

Alzheimer Disease↗
PubMed1983

Activation of the alternate complement pathway by peptidoglycan of Actinomyces viscosus, a potentially pathogenic oral bacterium.

Peptidoglycans and cells walls from Actinomyces viscosus, Staphylococcus aureus, and group A streptococcus were compared for their relative abilities to activate the alternate complement pathway (ACP). On the dry-weight basis, the peptidoglycan from A. viscosus was 3.5 times more active than group A streptococcal peptidoglycan and 15.6 times more active than Staph. aureus peptidoglycan in activating the ACP. Consequently A. viscosus peptidoglycan is one of the most potent ACP-activators reported to date. For both A. viscosus and group A streptococcus, the peptidoglycan was a better ACP activator than cell walls from the same organism (125- and 52-fold, respectively) indicating that the peptidoglycan is probably the most important subcellular ACP-activator in these microorganisms. In contrast, cell walls from Staph, aureus were 9 times more active than peptidoglycan from Staph. aureus in activating the ACP, presumably because teichoic acids are the most important subcellular ACP activator in this microorganism.

Actinomyces↗
PubMed1985

Peptidoglycan from the potentially pathogenic oral bacterium Actinomyces viscosus is a B-cell mitogen.

Cell walls and peptidoglycan from Actinomyces viscosus, strain M-100 were compared for their ability to act as mitogens with spleen cells from germ-free Fischer rats. The cell walls were prepared from trypticase soy broth grown whole cells using a French press, followed by two consecutive washes with 0.1 M tris-HCl buffer, pH 8.0, 1 M NaCl and distilled water. Peptidoglycan was prepared from cell walls by three consecutive formamide extractions at 165 degrees C. On a dry-weight basis, the peptidoglycan was a significantly-better mitogen than cell walls, suggesting that the peptidoglycan is the major mitogenic component of A. viscosus cell walls. Mononuclear spleen cells were separated on a Nylon-wool column into a non-adherent subpopulation enriched for T lymphocytes and a weakly-adherent, plunger-removable subpopulation enriched for B lymphocytes. The non-adherent T-cell subpopulation responded strongly to the T-cell mitogen PHA, but was unresponsive to both the peptidoglycan and cell walls from A. viscosus. In contrast, the weakly-adherent enriched B-cell subpopulation was less responsive to PHA, but was strongly stimulated by A. viscosus peptidoglycan and cell walls. These results indicate that peptidoglycan and cell walls from A. viscosus are B-cell mitogens.

Actinomyces↗
PubMed1989

Pathogenic potentials of bacterial proteases.

Six separate molecular mechanisms for pathogenesis attributed to bacterial proteases are described. (I). Enhancements of vascular permeability and edema formation which result from the activation of kinin generating cascade such as Hageman factor by the proteases. (II). Degradation of defense oriented proteins including IgG and IgA as well as destruction of structural matrices such as fibronectin, proteoglycan and collagen. (III). Inactivation of complement system and generated chemotactic factor from C3 and C5. (IV). Degradation of regulatory plasma protease inhibitors (serpins) including alpha 1-protease inhibitor, alpha 2-macroglobulin (alpha 2M), C1-esterase inhibitor, alpha 2-antiplasmin and antithrombin-III. (V). The protease forms a transitory stable enzyme/inhibitor(alpha 2M) complex. It binds to and internalizes into the cells which possess alpha 2M-receptor such as fibroblasts via the alpha 2M-receptor, and the protease activity is regenerated in cells, and subsequently intracellular integrity is destroyed resulting in cell killing. (VI). The serratial 56 kDa (56K) protease is found to potential viral yield 100 fold more when influenza virus infected mice were subjected to administrations of this protease intranasally. This results in rapid and much elevated lethality.

Animals↗