Dissertations and Theses @ UNI


Open Access Thesis


Amyotrophic lateral sclerosis--Environmental aspects; Acetylcholinesterase; Academic theses;


The purpose of this study was to analyze the red blood cell acetylcholinesterase (RBC AChE) reactivity levels among persons with amyothropic lateral sclerosis (PALS) (cases) and their controls when challenged with the oxon form of the organophosphate insecticide chlorpyrifos. The ultimate objective was to determine if a correlation exists between the RBC AChE reactivity level and the participants' disease status and/or exposure to toxins through occupations and hobbies.

Cases in this study were individuals diagnosed by a neurologist with sporadic ALS. Controls were individuals who were not genetically related to the PALS and were neuromuscular disease free. Controls were a spouse and/or a friend, in-law, or neighbor who was age and gender matched to the PALS. The study encompassed 54 participants (24 cases and 30 controls) who were residing in Iowa, Illinois, Minnesota or eastern Nebraska. The gender breakdown included 30 males (17 cases, 13 controls) and 24 females (7 cases, 17 controls). All participants completed an exposure assessment survey that required them to recall general medical history, disease progression (for the PALS) residential and occupational history, hobbies, dietary and laundry habits (only the occupational history and hobbies will be utilized for this study). Then, through in vitro analysis using whole blood, the RBC AChE reactivity was measured for each participant. The blood samples were then directly challenged with three dosage levels of chlorpyrifos-oxon and measured again. An enzyme reactivity rate comparison was made between the cases and the controls.

The participants, both cases and controls, showed a higher than expected range in plasma reactivity (unclosed). Among cases, 79.2% were above (N = 19) and 90% of controls were above (N = 27). The normal expected range, stated in the Teco Diagnostic reagent instructions, is 1,700 - 4,100 U/L. The participants had a range of 2,524.8 U/L to 8,346.8 U/L (M = 5,606.64 U/L) with the means for cases and controls closely related (M = 5,767.0 U/L and 5,406.1 U/L, respectively).

Analysis of room temperature showed a correlation with hemolysate and RBC AChE reactivity levels. The blood samples that were conducted at the lowest room temperature of 19° C had the lowest reactivity levels when compared to those ran at 21 ° C and 23° C. These higher temperatures affected eight participants, which were comprised of five controls and three cases.

Disease status (case or control), with the exclusion of the eight samples ran at higher temperatures, played a slight role in middle to low dosage levels for RBC AChE. Cases showed higher levels of activity for RBC AChE middle dosage level, which was not quite significant (ANOVA, f-ratio = 3.8437, p = 0.0564) and then showed lower reactivity levels for the RBC AChE low dosage level reactivity (ANOVA, f-ratio = 6.5811, p = 0.0139). Cases also had lower reactivity levels for hemolysate low dosage (ANOVA, fratio = 5.3580, p = 0.0255).

With the exclusion of the eight participants, a correlation was found with participants who had less than 8 hours per day of exposure to toxins (6 cases, 11 controls). These participants had lower RBC AChE levels at the high and middle dose level than those who were exposed to more than 8 hours (ANOVA, f-ratio = 5.6318, p = 0.0082; ANOVA, f-ratio = 7.6523, p = 0.0020, respectively). Only 34 of the 54 participants (63%) could recall this information and there was no significance found with regard to disease status.

This study found no clear correlation between RBC AChE reactivity levels and the participants' disease status and/or exposure to toxins through occupations and hobbies. Cases and controls were evenly matched in most analysis or reactivity levels. ALS is a very perplexing disease with no clear etiology or physiology. Researchers continue to look in multiple directions to discover the critical pieces of information that will eventually lead to a viable treatment and cure for those afflicted.

Year of Submission


Degree Name

Master of Science


Department of Health, Recreation, and Community Services


School of Health, Physical Education, and Leisure Services

First Advisor

Catherine Zeman


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Date Original


Object Description

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