Comparison of the effect of amniotic membrane suspension and autologous serum on alkaline corneal epithelial wound healing in the rabbit model.

PURPOSE: Alkaline corneal epithelial wound closure rates in rabbit eyes were compared after topical applications of amniotic membrane suspension, autologous serum, or preservative-free artificial tears. METHODS: Thirty rabbits were divided into 3 randomization groups of 10 rabbits each. Central corneal alkali wound was produced in both eyes of the rabbits by applying a 5-mm round filter paper, soaked in 1 N NaOH, for 60 seconds. Group 1 animals received preservative-free artificial tears in 1 eye and amniotic membrane suspension in the other eye; group 2 animals received preservative-free artificial tears in 1 eye and autologous serum in the other eye; and group 3 animals received autologous serum in 1 eye and amniotic membrane suspension in the other eye. The treatment was dosed 4 times a day with the eyedrops, and epithelial wound closure was recorded using slit lamp. The data were analyzed to determine the rate of wound closure. RESULTS: The mean wound radius closure rate was 67.8 +/- 5.2 microm/h for autologous serum-treated eyes, 74.5 +/- 5.4 microm/h for amniotic membrane suspension-treated eyes, and 66.8 +/- 5.0 microm/h for preservative-free artificial tear-treated eyes. CONCLUSIONS: This study shows that alkali-injured corneal epithelial wounds heal faster when treated with amniotic membrane suspension than with autologous serum or preservative-free artificial tears.

Investigation of organic, inorganic and synthetic adsorbents for the pretreatment of landfill leachate.

An investigation into the use of organic, inorganic and synthetic adsorbents for the pretreatment of landfill leachate, generated by the City of Ottawa Trail Road Landfill, was carried out. The purpose of this project was to reduce the concentration of contaminants in order to meet the local Sewer Use By-Laws, prior to transporting the leachate from the generating site to the local municipal sewage treatment plant, and thereby reducing the disposal fees. Peat moss, compost, clinoptilolite, basalt and two types of activated carbon (DSR-A and F400) were investigated to determine the adsorption capacity for contaminants from leachate. Kinetic studies were also performed. The results based on batch adsorption isotherms show that peat moss has the highest adsorption capacity for boron (B) and barium (Ba), compared with the other adsorbents. Also peat moss has good removals of Total Kjeldahl Nitrogen (TKN), Total Organic Carbon (TOC), and benzene, toluene, ethylbenzene and xylene (BTEX), but these are lower than the removals obtained with activated carbon. Because of its relatively low cost and higher adsorption of B and Ba, peat moss was selected as the filter media for the column studies. The treated leachate was tested for B, Ba, TKN, carbonaceous biological oxygen demand (CBOD5) and hydrogen sulfide (H2S). The breakthrough curves for B and Ba showed the effectiveness of peat moss in removing these contaminants.

Characterization of Giardia duodenalis isolates from a waterborne outbreak.

Isolates were retrieved from drinking water and from animal and human sources associated with a waterborne outbreak of giardiasis. This is the first report of water-source and epidemic-associated Giardia isolates being adapted to in vitro propagation. Outbreak-associated, non-out-break-associated, and reference isolates were characterized using isoenzyme electrophoresis and pulsed-field gel electrophoresis (PFGE). All outbreak-associated and 2 other isolates were in one of eight zymodemes. The chromosomal complement of the outbreak-associated isolates was relatively homogeneous; this PFGE karyotype was distinguishable from other karyotypes. Overall results of both characterization methods were similar, although PFGE appears to be a more discriminating biotyping technique. Banding patterns of the outbreak-associated Giardia isolates remained the same even though the parasite passed through different hosts during the outbreak. Heterogeneity of isolates was also demonstrated for the first time within a single community not associated with the outbreak.

Comparison of an in vitro method and an in vivo method of Giardia excystation.

An in vitro method and an in vivo method of excystation were compared to determine the most useful method for the retrieval of Giardia duodenalis isolates. Cysts from 11 Giardia strains were used. In vitro excystation produced motile trophozoites in 16 sets, while in vivo excystation produced trophozoites in all of the 21 comparative sets of excystations. Few cultures were lost because of contamination by either method (17% of in vitro-derived trophozoites versus 23% of in vivo-derived trophozoites; P greater than 0.05). Both methods demonstrated comparable isolate retrieval rates (15% of in vitro-derived trophozoites adapting to culture compared with 29% of in vivo-derived trophozoites; P greater than 0.05), although analysis of the strains retrieved showed that two isolates were retrieved from in vitro excystation alone, compared with four from in vivo excystation. Analysis that included results of extra in vivo cultures showed that a total of nine isolates were retrieved by using this type of excystation. Despite the disadvantages of cost and labor, in vivo excystation appears to be more useful than in vitro excystation for isolate retrieval at the present time.