Sodium Metabisulfite Inhibits Acanthamoeba Trophozoite Growth through Thiamine Depletion.

Acanthamoeba keratitis (AK) is a severe infection of the cornea. Prevention and treatment are difficult due to the inefficacy of currently available compounds. The impact of many commonly used compounds for routine examinations of Acanthamoeba is unexplored but might offer insight useful in combatting AK. In this study, we demonstrate that sodium metabisulfite, a common preservation constituent of eye care solutions, was found to be active against Acanthamoeba trophozoites at concentrations lower than that commonly found in eye drops (IC50 0.03 mg/mL). We demonstrate that sodium metabisulfite depletes thiamine from growth medium and that Acanthamoeba is a thiamine auxotroph, requiring thiamine salvage for growth. The inhibitory effects of sodium metabisulfite can be overcome by thiamine supplementation. These results are consistent with the lack of key enzymes for thiamine biosynthesis in the genome of Acanthamoeba, an area which might prove exploitable using new or existing compounds. Indeed, this study highlights sodium metabisulfite as a useful inhibitor of Acanthamoeba castellanii trophozoites in vitro and that it acts, at least in part, by limiting available thiamine.

Description and prevalence of gregarines infecting the amphipod Gammarus pulex, in the Water of Leith, Scotland, UK.

Gregarines are symbiotic protists that are found in a broad spectrum of invertebrates, including insects, crustaceans, and annelids. Among these the globally distributed amphipod Gammarus pulex is one of the earliest recognized hosts for aquatic gregarines and is prevalent among macroinvertebrates in freshwater environments. In this study, samples of G. pulex were collected in the Water of Leith river, Scotland, UK. Gregarines were identified using light and scanning electron microscopy as well as standard molecular techniques. We identified three septate eugregarine symbionts-Heliospora longissima, Cephaloidophora gammari, and the here newly characterized Cephaloidophora conus n. sp. (formerly Cephaloidophora sp.) associated with Gammarus pulex in the Water of Leith. Prevalences for identified gregarine species were calculated and seasonal dynamics of gregarine infections/colonization were analyzed. Prevalences were highest in autumn and spring reaching almost 50 %. While the two Cephaloidophora species showed similar colonization patterns, the prevalence of Heliospora showed an opposite trend. Identifying gregarine infection/colonization patterns is one step towards better understanding the gregarine-host relationship, as well as possible impacts of the gregarines on their hosts.

The toxicity of potentially toxic elements (Cu, Fe, Mn, Zn and Ni) to the cnidarian Hydra attenuata at environmentally relevant concentrations.

The domestic, agricultural, industrial, technological and medical applications of potentially toxic elements (PTEs) have led to global pollution in all environments. In this study, the cnidarian Hydra attenuata was exposed individually and to a mixture of 5 metals (copper, iron, manganese, zinc and nickel) at environmentally relevant concentrations (1×) within the Clyde estuary, Scotland and incremental concentrations ranging from 0.0001× to 1000×. Toxicity was investigated using morphology, attachment, hydranth number and feeding behaviour as endpoints. When exposed individually, Cu, Mn and Fe significantly reduced Hydra morphology, feeding and attachment at environmentally relevant concentrations. Hydra mortality was measured, having an LC50 of 0.045× (for the environmentally relevant mixture of metals) and Cu 0.5 mg/l, Fe 3 mg/l, Mn 2 mg/l, Zn 0.1 mg/l, Ni 0.5 mg/l for each element exposed individually. The PTE mixture incurred a significant decrease (p ≤ 0.05) in morphology at 0.0001×, with 100% mortality at 0.1× (containing a concentration of Cu 0.05 mg/l, Fe 0.3 mg/l, Mn 0.2 mg/l, Zn 0.01 mg/l, Ni 0.05 mg/l) and a toxicity threshold (TT) of 0.000005×. Both copper and iron when exposed individually to the concentration of their respective metals found in the environment resulted in 100% mortality for all Hydra exposed. These results indicate that the PTE mixture (including the individual concentrations of copper, iron, manganese and nickel) could potentially prove significantly toxic to the aquatic environment.

Catheter-based treatment for patients with acute ischemic stroke ineligible for intravenous thrombolysis.

BACKGROUND AND PURPOSE: We present our single-center experience using catheter-based therapy for acute ischemic stroke patients who were not candidates for intravenous thrombolytic therapy. METHODS: Neurologic outcomes were assessed in patients with acute ischemic stroke, ineligible for intravenous thrombolysis, treated with an emergent catheter-based therapy. RESULTS: Nonparametric analysis of neurological outcomes demonstrated a benefit in National Institutes of Health Stroke Scale (NIHSS) at long-term follow-up (P=0.036). Independence in daily activities and improvement in NIHSS of > or =4 points were achieved in 38% and 56% of patients, respectively. Four patients (25%) died, including 2 patients (12.5%) who died from intracranial hemorrhage. CONCLUSIONS: Catheter-based treatment offers a promising treatment strategy in patients with acute ischemic stroke ineligible for intravenous thrombolysis.

Carotid stents to prevent stroke: a nonsurgical option.

Angioplasty and stent placement have become accepted alternatives to surgery in many vascular territories. The most recent application of percutaneous intervention has been to explore its clinical utility and safety for stroke prevention in carotid arteries. Over the past 8 years, from January 1994 until Nov 2002, we performed 449 elective carotid stent procedures in 426 patients and in 481 vessels. Informed consent was obtained from each patient. Success was achieved in 97.3% of the patients treated. After one month of follow-up, 12 (2.8%) patients experienced stroke or death. After an average of 2.8 ± 1.7 years (range 1 month to 8.8 years) of follow-up, restenosis was found in 11 (2.6%) patients and was treated with balloon angioplasty. Our results, in a predominantly high-risk surgery group of patients, suggest that carotid stent placement is a viable treatment alternative to conventional surgery. It is likely that as the technology continues to evolve, the procedural risks of stroke and death will be minimized by embolic protection devices, making carotid stenting an option for low-risk surgical patients.