Free-living amebae are ubiquitous in the environment and occasionally invade and parasitize host tissues causing illness in humans. Despite possibly frequent exposure to these organisms, infection is rare and why some people, healthy or not, end up with illness and others do not is still unclear. Human infections are rare; when illness does occur, it is often fatal. Only two papers have examined data from the literature and cases reported to the Centers for Disease Control and Prevention, and both were published over twenty years ago. The purpose of this study is to better document the epidemiology of Balamuthia and non-keratitis Acanthamoeba, give insight into trends of these infections over time, and contribute to the scientific and medical community by producing the only comprehensive review of all Balamuthia and non-keratitis Acanthamoeba cases in the United States from 1955 through 2009. This study also examines cases that have survived in an attempt to determine if there is evidence for the effectiveness of a particular treatment regimen. Only a small number of patients have survived these infections, so any evidence for a successful course of treatment could be crucial for future cases.

Free-living pathogenic amoebae Acanthamoeba spp. and Balamuthia mandrillaris are causative agents of important diseases of human: rarely occurring but highly fatal granulomatous amoebic encephalitis (both) and keratitis (Acanthamoeba). One of the reasons for the problematic therapy is differentiation into highly resistant cysts often found in affected tissues. In our study we have found that correct encystation in Acanthamoeba requires apart from others, the presence of functioning Golgi apparatus transporting the cyst wall material to the cell surface; glycogen phosphorylase degrading glycogen into glucose which seems to be further used for cellulose synthesis and two non-constitutive cellulose synthases. Acanthamoeba cellulose synthases seem not to be inhibited by known herbicides. In the cyst wall of acanthamoebae we detected cellulose, -mannan, and -1, 3-1, 4-linked glucan [lichenin or mixed-linkage glucan (MLG)]. Cellulose is present in the inner (endocyst) and the outer (exocyst) layers of the cyst wall, whereas-mannan and MLG are found in the endocyst. In a protozoan organism, MLG was detected for the first time. The MLG of Acanthamoeba has a similar composition to that found in barley with high amount of cellobiosyl and cellotriosyl followed by cellotetraosyl units. In contrast, with...

<p dir="ltr">Cyclic peptides are a growing drug class with over 40 FDA-approved drugs, with natural product cyclic peptides being the inspiration for many of these medicines (e.g., the antibiotic daptomycin, the immunosuppressant cyclosporine A, and the antifungal caspofungin). Two major types of cyclic peptide natural products exist: (1) the ribosomally synthesized and post-translationally modified peptides (RiPPs) and (2) those made by nonribosomal peptide synthetases (NRPSs). Even though many uncharacterized cyclic peptide biosynthetic gene clusters (BGCs) exist, the discovery of new cyclic peptide natural products remains a challenge because many BGCs are cryptic. Herein, we describe the development of a new approach to access the products of these cryptic NRPS BGCs and the discovery of many novel bioactive compounds from this approach. Specifically, we utilized bioinformatics programs to predict the amino acid sequences associated with the multimodular NRPS and the presence of a nearby penicillin-binding protein (PBP)-like thioesterase (TE, PBP-TE) to determine that the predicted peptides are head-to-tail cyclized. Following the bioinformatics-guided predictions, solid phase peptide synthesis (SPPS) followed by solution phase cyclization enabled access to a library of predicted cyclic peptides that we then screened for interesting bioactivities. From this screening, we have identified molecules that stimulate the proteasome, inhibit the growth of free-living amoebas, selectively lyse Gram-negative bacteria, and suppress the immune system. Structure activity relationships for these molecules have been determined, with more potent analogs being discovered. Future directions include mechanism of action studies, as well as expanding the peptide library to include more off-loading methods and tailoring enzymes that might modify the peptide after release from the NRPS.</p>