Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022568 (keratitis)
 5,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acanthamoeba spp. are among the most prevalent protozoa found in the environment. The species of this genus are the causative agents of granulomatous amebic encephalitis (GAE), a fatal disease of the central nervous system (CNS), and amebic keratitis (AK), a painful sight-threatening disease of the eye. In this study we have used two species of Acanthamoeba, Acanthamoeba castellanii and A. hatchetti, both were obtained from Vienna, Austria. They were cultivated on non-nutritious agar seeded with Escherichia coli and PPYG (protease peptone-yeast extract-glucose) medium. Our aim was to concentrate on three points in relation to the trophozoites and cysts stages of these species as follows: (i) to observe their morphology, (ii). to confirm our previous observation of a canal between two trophozoites. The bridge-like connection between these trophozoites greatly resembled the one that can be observed in conjugation during an exchange of genetic material. Two tro-phozoites with a bridge-like extension between them keep their position for at least 200 minutes. (iii). to detect the reactions of trophozoites to various stains. According to our findings in regard to these three points: (i). trophozoites with more than one nucleus are often seen in axenic cultures. (ii). This resembles a type of conjugation with a transfer of genetic material between two trophozoites. Certainly, this needs further investigation using more sophisticated methods. (iii). trophozoites equally stained well with Heidenhain's iron haematoxylin, Giemsa, PAS, Masson Trichrome, and Toludin-O stains. However, our results with reticulin, PAP, Van Gison, Musicarmine and Orsein stains were not satisfactory.
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PMID:[Observations on Acanthamoeba trophozoites in axenic cultures and their staining characteristics with different stains]. 1747 4

Acanthamoeba spp. consists of free-living amoebae, widespread in nature, which occasionally can cause human infections including granulomatous amoebic encephalitis and amoebic keratitis. Acanthamoeba pathogenesis is not entirely known and correlations between pathogenic potential and taxonomy are complex issues. In order to decipher the definition of a pathogenic amoeba, the objective of this work was to decipher the definition of pathogenic amoeba by characterizing two isolates of Acanthamoeba polyphaga obtained from different origins (a keratitis patient and freshwater), looking for differences among them. The clinical isolate grew faster in Peptone-yeast extract-glucose (PYG) medium, transformed more rapidly from a trophozoite to cyst and exhibited increased cytopathic effect on cultured cells. Morphological differences were also noted, since freshwater amoebae presented more acanthopodia than the clinical isolate. Moreover, actin labeling demonstrated that microfilament organization varies between isolates, with the presence of locomotory structures as lobopodia and lamellipodia in the keratitis isolate, which were less adherent on plastic. Zymography demonstrated that the keratitis isolates presented higher proteolytic activity and also were more able to invade collagen matrices. Altogether, we conclude that a group of stable physiological characteristics exist in Acanthamoeba that can be related to pathogenicity.
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PMID:Biological characterization of a clinical and an environmental isolate of Acanthamoeba polyphaga: analysis of relevant parameters to decode pathogenicity. 1756 30

Herpes simplex virus encephalitis (HSE) is the most common fatal sporadic encephalitis in humans. HSE is primarily caused by herpes simplex virus (HSV)-1 infection of the brain. HSE results in increased levels of oxidative stress, including the production of reactive oxygen species, free radicals, and neuroinflammation. The most biologically active form of vitamin E (VE) is alpha-tocopherol (alpha-TOC). In cellular membranes, alpha-TOC prevents lipid peroxidation by scavenging free radicals and functioning as an antioxidant. Supplementation with VE has been shown to decrease immunosenescence, improve immune function, and may be neuroprotective. To determine how VE deficiency and VE supplementation would alter the pathogenesis of HSE, we placed weanling male BALB/cByJ mice on VE-deficient (VE-D), VE-adequate (VE-A), or 10x VE-supplemented diets for 4 wk, and then infected the mice intranasally with HSV-1. VE-D mice had more severe symptoms of encephalitis than VE-A mice, including weight loss, keratitis, hunched posture, and morbidity. VE-D mice had increased cytokine and chemokine expression in the brain and increased viral titers. In contrast, VE supplementation failed to decrease cytokine production and had no effect on viral titer. We demonstrated that adequate levels of VE are important in limiting HSE pathology and that 10x supplementation does not enhance protection.
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PMID:The immune response to herpes simplex virus encephalitis in mice is modulated by dietary vitamin E. 1815 15

Herpes simplex virus type 1 (HSV-1) produces oral lesions, encephalitis, keratitis, and severe infections in the immunocompromised host. HSV-1 is almost as common as HSV-2 in causing first episodes of genital herpes, a disease that is associated with an increased risk of human immunodeficiency virus acquisition and transmission. No approved vaccines are currently available to protect against HSV-1 or HSV-2 infection. We developed a novel HSV vaccine strategy that uses a replication-competent strain of HSV-1, NS-gEnull, which has a defect in anterograde and retrograde directional spread and cell-to-cell spread. Following scratch inoculation on the mouse flank, NS-gEnull replicated at the site of inoculation without causing disease. Importantly, the vaccine strain was not isolated from dorsal root ganglia (DRG). We used the flank model to challenge vaccinated mice and demonstrated that NS-gEnull was highly protective against wild-type HSV-1. The challenge virus replicated to low titers at the site of inoculation; therefore, the vaccine strain did not provide sterilizing immunity. Nevertheless, challenge by HSV-1 or HSV-2 resulted in less-severe disease at the inoculation site, and vaccinated mice were totally protected against zosteriform disease and death. After HSV-1 challenge, latent virus was recovered by DRG explant cocultures from <10% of vaccinated mice compared with 100% of mock-vaccinated mice. The vaccine provided protection against disease and death after intravaginal challenge and markedly lowered the titers of the challenge virus in the vagina. Therefore, the HSV-1 gEnull strain is an excellent candidate for further vaccine development.
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PMID:A replication-competent, neuronal spread-defective, live attenuated herpes simplex virus type 1 vaccine. 1856 43

Members of the genus Acanthamoeba, amphizoic protozoan parasites, are causative agents of granulomatous amoebic encephalitis and amoebic keratitis. Proteinases play a role in various biologic actions in Acanthamoeba, including host tissue destruction, pathogenesis, and digestion of phagocytosed food. Interestingly, we found that encystation of Acanthamoeba was inhibited by the serine proteinase inhibitor phenylmethanesulfonyl fluoride. In this study, we characterize a serine proteinase that is involved in mediating the encystation of Acanthamoeba. This encystation-mediating serine proteinase (EMSP) is shown to be highly expressed during encystation by real-time PCR and Western blot analysis. Chemically synthesized small interfering RNA against EMSP inhibited the expression of EMSP mRNA and significantly reduced the encystation efficiency of Acanthamoeba. An EMSP-enhanced green fluorescent protein fusion protein localized to vesicle-like structures within the amoeba. Using LysoTracker analysis, these vesicular structures were confirmed to be lysosomes. After incubation of the transfected amoeba in encystment media, small fluorescent vesicle-like structures gathered and formed ball-like structures, which were identified as colocalizing with the autophagosome. Taken together, these results indicate that EMSP plays an important role in the differentiation of Acanthamoeba by promoting autolysis.
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PMID:Characterization of a serine proteinase mediating encystation of Acanthamoeba. 1867 58

Acanthamoeba is a free-living ameba that is found throughout the world and that causes encephalitis, keratitis, and cutaneous infections in humans. It has two stages in its life cycle: a trophic stage and a resistant cyst stage. We describe here the ability of Acanthamoeba cysts to survive desiccation for more than 20 years.
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PMID:Survival of Acanthamoeba cysts after desiccation for more than 20 years. 1892 13

The infection of humans with the rodent-borne lymphocytic choriomeningitis virus (LCMV) can lead to central nervous system disease in adults or severe neurological disease with hydrocephalus and chorioretinitis in children infected congenitally. Although LCMV-induced meningitis and encephalitis have been studied extensively, the immunopathological mechanisms underlying LCMV infection-associated ocular disease remain elusive. We report here that the intraocular administration of the neurotropic LCMV strain Armstrong (Arm) elicited pronounced chorioretinitis and keratitis and that infection with the more viscerotropic strains WE and Docile precipitated less severe immunopathological ocular disease. Time course analyses revealed that LCMV Arm infection of the uvea and neuroretina led to monophasic chorioretinitis which peaked between days 7 and 12 after infection. Analyses of T-cell-deficient mouse strains showed that LCMV-mediated ocular disease was strictly dependent on the presence of virus-specific CD8(+) T cells and that the contribution of CD4(+) T cells was negligible. Whereas the topical application of immunosuppressive agents did not prevent the development of chorioretinitis, passive immunization with hyperimmune sera partially prevented retinal and corneal damage. Likewise, mice displaying preexisting LCMV-specific T-cell responses were protected against LCMV-induced ocular disease. Thus, antibody- and/or T-cell-based vaccination protocols could be employed as preventive strategies against LCMV-mediated chorioretinitis.
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PMID:Immunopathological basis of lymphocytic choriomeningitis virus-induced chorioretinitis and keratitis. 1894 66

Strains of Acanthamoeba sp. constitute a factor contributing to the occurrence of chronic granulomatous amoebic encephalitis, keratitis, pneumonia, as well as inflammations of other organs. Treatment of these diseases is very difficult and not always effective. A majority of these infections have been fatal. The aim of our study was to examine the amoebicidal or amoebistatic activity of plant extracts from Rubus chamaemorus, Pueraria lobata, Solidago virgaurea and Solidago graminifolia. For the purpose of isolation of pharmacologically active substances, we used the aboveground parts of plants, together with flowers, roots and leaves. It was established that extracts from S. virgauera, P. lobata and R. chamaemorus displayed chemotherapeutic properties in vitro in concentrations of approximately 0.01-0.05 mg extract/mL, i.e., in concentrations of 0.350 microg/mL expressed in ellagic acid for R. chamaemorus and 0.053 microg/mL expressed in puerarin for P. lobata. Therapeutic index values is 3.5-20. As a result of in vivo experiments, it was found out that, following therapy using the extracts, animals infected with Acanthamoeba sp. survived for an extended period (2.5-3 times longer). It was determined that plant extracts may be used both externally and internally in the case of a combined therapy for acanthamoebiasis. The tested extracts are not toxic for animals.
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PMID:Plant extracts as natural amoebicidal agents. 1905 Sep 23

Acanthamoeba is an opportunistic protozoan pathogen that can produce keratitis and rare but fatal encephalitis. In the present study, we examined secretory IgA antibody to Acanthamoeba castellanii of the T4 genotype in mucosal secretions from 114 individuals of 37 countries, inhabitants and/or visitors, aged 16-65 years in London, UK. Acanthamoeba antibody prevalence rate was more than 85%, without any significant differences between males (86.2%) and females (89.2%). Some epidemiological factors contributing to the high prevalence of antibody to Acanthamoeba in surveyed population are discussed further.
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PMID:Acanthamoeba castellanii: high antibody prevalence in racially and ethnically diverse populations. 1907 Nov 16

Acanthamoeba is an opportunistic protozoan pathogen that can cause blinding keratitis and a rare but fatal encephalitis involving the central nervous system with a very poor prognosis. This is due to limited availability of effective anti-acanthamoebic drugs. Here, we tested whether the use of liposomes can improve the potency of pentamidine isethionate, an anti-amoebic compound. The liposomes consisted of l-alpha-phosphatidylcholine and cholesterol or ergosterol in a molar ratio of 1 : 5. Pentamidine isethionate was incorporated to achieve a final drug to lipid ratio of 1 : 5. At a drug concentration of 10 microg ml(-1), the liposomal drug was >12 times more effective than the free drug at preventing Acanthamoeba binding to human cells and significantly more effective in reducing parasite-mediated human cell cytopathogenicity, compared with the drug alone. Both the free and liposomal drug blocked Acanthamoeba encystation.
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PMID:Effect of free versus liposomal-complexed pentamidine isethionate on biological characteristics of Acanthamoeba castellanii in vitro. 1920 82


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