Botulism is a foodborne intoxication caused by ingestion of Clostridium botulinum neurotoxin (BoNT). Preliminary studies focussed on the production of polyclonal antisera against BoNT/E by immunizing a rabbit with botulinal toxoid type E. The antiserum was subsequently used to detect BoNT/E using the slot blot immunoassay where samples were applied to a slot blot filtration manifold and drawn by vacuum through a membrane. The membrane was then immunologically processed before chemiluminescent detection. However, the antisera lacked specificity and cross-reacted with closely related clostridia strains. / The specificity of the antisera was increased by adsorbing cross-reactive antibodies from whole antisera with affinity columns made with total proteins from culture supernatants of closely related clostridia. Alternatively, specific antibodies were isolated with an affinity column prepared with C. botulinum type E toxoid. / Different methods of concentrating BoNT/E in each sample prior to testing them were evaluated to increase the sensitivity of the assay. / The slot blot immunoassay was then evaluated for detection of BoNT/E in mixed cultures and in food samples. (Abstract shortened by UMI.)

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1989. / Includes bibliographical references (leaves 147-156).

Thesis (M.S.)--Baylor University, 2007. / Includes bibliographical references (p. 44-46).

Thesis (M.A.S.)--University of Delaware, 2008. / Principal faculty advisor: Chin-Pao Huang, Dept. of Civil and Environmental Engineering. Includes bibliographical references.

M.Sc. (Zoology) / Axenic cultures of Euglena gracilis in different basal medium concentrations, to simulate eutrophic conditions, were exposed to different concentrations of Monocrotophos and Dichlorvos to determine the effect of the pesticides on the growth reaction. The effect of the pesticides on the chlorophyll a content of test organisms exposed to equivalent toxicities of pesticides was determined. The amount of pesticide accumulated and me tabolised was determined by the choline esterase method and by gaschromatography. More pesticide was found to be accumulated and metabolised by organisms in the lower concentration of basal medium.

Lesotho is experiencing a problem of seasonal bloody diarrhoea outbreaks that occur in the southern districts of the country. Usually large proportions of the meagre resources are used to combat such outbreaks. Measures have been taken to provide water and improve sanitation for the commonly affected communities. However, the problem has continued unabated. There was therefore, a need to isolate factors that are associated with the transmission of bloody diarrhoea among the communities in the Moriti, Holy Cross, Liphiring and Mohalinyane health centres where bloody diarrhoea is prevalent. In this study, 145 cases of bloody diarrhoea and 269 controls were selected from the four health centres. Cases and controls were selected from subjects who were seen in the health centres during the period of December 2002 to February 2003. All available cases were selected whereas controls were selected by systematic sampling. The study examined environmental factors such as water source, waste and refuse disposal and hygiene practices. Binary logistic regression was used to estimate the effects of several exposures on bloody diarrhoea. The model showed maintenance of the boreholes to be the most important variable. The Odds ratio among people who experienced unavailability of water was 3.88 greater, among children who do not wash hands the odds ratio was 4.66 higher. Among subjects who ate bread in January the Odds ratio was 1.45 more and among subjects who had someone with bloody diarrhoea in the household the Odds ratio was 2.60 greater. / Dissertation (MSc)--University of Pretoria, 2005. / School of Health Systems and Public Health (SHSPH) / MSc / Unrestricted

Aquatic toxicology has been identified as a valuable tool in the identification and management of chemical pollution in aquatic ecosystems. Standardised methodologies for acute aquatic bioassays have been adopted from international agencies. As a result of these standard methods, the use of laboratory cultured organisms for toxicity testing has been more popular than that of indigenous field-caught organisms. Included in these adopted methods are those for the cultured crustacean Daphnia pUlex. D.pulex is adapted to living in standing water and the suitability of this species to determine toxic effects for South African riverine environments, which are largely flowing, has been questioned. Thus this thesis is a case-study ofthe use of D.pulex and indigenous site-specific macroinvertebrates as toxicity test organisms for setting acute water quality guidelines to protect aquatic ecosystems. The study highlights site-specific problems such as reference sites and organism identification. The acute tolerance of selected indigenous invertebrates was compared to that of D. pulex, using both a single-substance reference toxicant (zinc) and selected whole efiluents. The significance of source population and culture age as a potential source of biological variability between D.pulex cultures was also investigated. D.pulex cultures have been initiated in South Africa from females collected from a number of different local populations; also it is assumed that no genetic change (due to mutation) occurs within a D.pulex culture over time. In order to establish if source population and culture age are a source of biological variability between D.pulex experiments, the acute tolerJuce to zinc of two different D.pulex populations and three different generations within a population were compared. Due to experimental variability results were inconclusive, and differences in tolerance as a result of population difference or culture age could not be determined with confidence. The acute tolerance of D.pulex to a single reference chemical (zinc) and selected whole efiluents was compared to that of selected indigenous invertebrates. Acute 48 h D.pulex zinc tolerance (LC50 range: 0.22 - 0.60 mg/l Zn) was found to be more sensitive than acute 96 h tolerances shown by mayfly species A.fconurus peringueyi (Heptageniidae) (LC50: 17.42 mg/l Zn), Euthrauluselegans (Leptophlebiidae) (LC50: 0.98 mg/IZn), Ba~tidae (LC50: 0.94mg/IZn) and shrimp, Caradina nilotica (Atyidae) (LC50: 3.17 mg/l Zn). This result suggests that guidelines for zinc set using D.pulex will protect the selected indigenous invertebrates. Selected whole eftluents were not acutely toxic to either D.pulex or selected indigenous invertebrates. These experiments were used as a case study for method development regarding the comparative use of D.pulex and indigenous invertebrates in acute whole eftluent toxicity testing. Finally, it is recommended that a suite of indigenous organisms (e.g. macroinvertebrates, fish and algae), as well as laboratory cultured D.pulex, be used in the initial setting of guidelines and that D.pulex be used for routine compliance monitoring. It is futher recommended that a suite of available monitoring methods, such as chemical and biomonitoring methodologies, be used in conjuction with toxicity testing in water quality management.

No description available.

This research is part of an overall program to develop and use a suite of acute and sublethal toxicity biomarkers, and testing protocols for use in assaying potential effects of complex mixtures of xenobiotics such as found in soils containing agricultural biocides and petrochemical wastes dredged sediments, and hazardous waste sites (HWS). The purpose of this study was to evaluate four biomarkers of sublethal pathology that could be used in an integrative model of multiple toxicity endpoints with the earthworm Lumbricus terrestris.

The feasibility of using rat liver mitochondria respiratory parameters as a short-term toxicity test was investigated. Mitochondrial fractions were exposed to six concentrations of five chlorophenols. Respiratory parameters were measured and compared to control experiments. The toxicity of the chlorophenos, measured by the 50% uncoupling concentration (UC50), increased with increasing chloro substitution. The UC50 values for the five chlorophenols were compared to six physicochemical parameters for the same chlorophenols and high degrees of correlation were found (r >/- 0.890). The highest correlation coefficient obtained was with the octanol-water partition coefficient. UC50 values were also compared to nine currently existing short-term toxicity tests. High degrees of correlation were obtained with several of these tests, including bacterial and fish bioassays. From the results of these experiments, the measurement and use of mitochondria respiratory parameters as a short-term toxicity test appears to offer an alternative to currently used short-term toxicity tests, particularly with chemicals having physicochemical characteristics similar to mitochondria uncouplers. / Master of Science