title: Examination of the Molecular Mass of Polyhydroxypolyamides

authors: Faville, Martyn

subjects: Polyhydroxypolyamides

abstract: The work described in this thesis investigated the use of size exclusion chromatography (SEC) to fractionate a variety of different polyhydroxypolyamide (PHPA) samples for analysis by matrix assisted laser desorption ionisation-time of flight spectrometry (MALDI-TOF). The molecular weights obtained via MALDI-TOF were then compared to those obtained by 1H nuclear magnetic resonance (NMR) end-group analysis.
Deionised water was used as the solvent for SEC fractionation using KS sugar columns KS-804 and 805 in series. An issue with PHPA is the possibility that they may hydrolyse in water and also under elevated temperature. Since deionised water was used to prepare each sample and they were run through columns which were under elevated temperatures (50˚C) hydrolysis could occur during fractionation by SEC. Through 1H NMR degradation experiments at room temperature and at 50˚C, it was observed that degradation would not be a problem.
Analysis of each PHPA sample on each KS sugar column showed fractions in the V0 region. These fractions make up the majority of the composition of unfractionated PHPA samples. There are two possible explanations for these fractions in this region, these are; 1) smaller ionised molecular weight PHPA polymers and 2) extremely high molecular weight PHPA polymer fractions. From the resulting SEC, MALDI and 1H NMR T2 relaxation rate measurements, it was concluded that these fractions are extremely high molecular weight polymer fractions.
The size of these PHPA fractions means molecular weights cannot be determined for these fractions and for unfractionated PHPA samples due to the limitations of MALDI-TOF spectrometry and 1H NMR end group analysis. However MALDI-TOF and 1H NMR end-group analysis do give good predictions for low molecular weight PHPA fractions which are in agreement with each other.

text: Examination of the Molecular Mass of Polyhydroxypolyamides The work described in this thesis investigated the use of size exclusion chromatography (SEC) to fractionate a variety of different polyhydroxypolyamide (PHPA) samples for analysis by matrix assisted laser desorption ionisation-time of flight spectrometry (MALDI-TOF). The molecular weights obtained via MALDI-TOF were then compared to those obtained by 1H nuclear magnetic resonance (NMR) end-group analysis.
Deionised water was used as the solvent for SEC fractionation using KS sugar columns KS-804 and 805 in series. An issue with PHPA is the possibility that they may hydrolyse in water and also under elevated temperature. Since deionised water was used to prepare each sample and they were run through columns which were under elevated temperatures (50˚C) hydrolysis could occur during fractionation by SEC. Through 1H NMR degradation experiments at room temperature and at 50˚C, it was observed that degradation would not be a problem.
Analysis of each PHPA sample on each KS sugar column showed fractions in the V0 region. These fractions make up the majority of the composition of unfractionated PHPA samples. There are two possible explanations for these fractions in this region, these are; 1) smaller ionised molecular weight PHPA polymers and 2) extremely high molecular weight PHPA polymer fractions. From the resulting SEC, MALDI and 1H NMR T2 relaxation rate measurements, it was concluded that these fractions are extremely high molecular weight polymer fractions.
The size of these PHPA fractions means molecular weights cannot be determined for these fractions and for unfractionated PHPA samples due to the limitations of MALDI-TOF spectrometry and 1H NMR end group analysis. However MALDI-TOF and 1H NMR end-group analysis do give good predictions for low molecular weight PHPA fractions which are in agreement with each other.

year: 2010

title: The effects of multiple sclerosis: Exploring executive dysfunction and its linkswith other cognitive impairment

authors: Drew, Margaret A.

abstract: Multiple Sclerosis (MS) is one of the most common chronic diseases of the central nervous system, and in New Zealand an estimated 4,000 people are currently affected. Although the physical manifestations of the disease are well known, and memory impairments have been comparatively well researched, those cognitive abilities known collectively as executive functions, and their relationship with other cognitive processes, have seldom been examined.
To fill this research gap, the present study examined the extent and nature of executive dysfunction and other cognitive impairments in a community based sample of participants with MS, and explored any links between executive dysfunction and other cognitive processes. Due to the well known heterogeneous nature of the effects of MS, impairment was assessed not only for the sample as a whole, but more informatively, and in contrast to much of the previous research on MS, within smaller more homogeneous groups formed on the basis of the extent and nature of the cognitive impairment of the participants. As the behavioural characteristics of executive dysfunction may have an influence on the ability to function appropriately on a daily basis in the community at large, evidence of typical 'dysexecutive' behaviour was also examined.
Ninety five participants with MS were assessed on general ability (WAIS-III), memory (WMS-III), executive functioning (D.KEFS), information processing speed and simple attentional processes. While the extent of impairment remained low on general ability measures, some impairment became evident in over half of the participants with MS on the memory measures. Five categories of executive functioning were used to assess the extent and nature of executive dysfunction; Inhibition, Shifting, Reasoning, Planning and Fluency. Working memory was not included as an executive category, as the primary scores obtained from the D.KEFS assessment did not enable this process to be isolated. Working memory was however evaluated as part of the memory assessment (WMS - III). Over half the participants were found to be impaired in at least one category of executive dysfunction, and the most commonly impaired categories were fluency and reasoning. Although sixteen different profiles of executive dysfunction were evident amongst the participants, the majority of those impaired were assessed with only one category of impairment. Surprisingly, no impairment in information processing speed was evident, but some participants were impaired in relation to simple attentional processes. 
The participants with MS were subsequently divided into four groups based on the nature of their impairment, that is, depending on whether the participant had no impairment, memory impairment only, memory impairment and executive dysfunction or executive dysfunction only. The index scores for visual memory were found to be consistently lower than those for auditory memory for all the 'impairment type' groups, but little difference was found between long-term and short-term memory performance. Working memory was found to be the only cognitive process which differentiated between those groups with executive dysfunction and those without, and at all levels of performance, proved to be a reliable predictor of the degree of executive dysfunction. Working memory was also found to have a differing relationship with each of the other five specific categories of executive functioning. 
When the everyday behavioural characteristics of executive dysfunction, such as inhibition, intentionality, executive memory and positive and negative affect were assessed with the Dysexecutive Questionnaire, there was little evidence of any self reported problems. In particular, levels of insight were shown not to be compromised, therefore it seemed that if any behavioural difficulties did arise for the participants, they would have been able to recognize and subsequently address them. Thus, it appeared for this sample of participants with MS that although some executive dysfunction was more prevalent than had previously been suggested in the literature on MS, generally the living arrangements of these participants seemed appropriate in relation to their ability to function independently. 
Overall, it was recommended that for the initial cognitive assessment of those with MS, a comprehensive evaluation of working memory integrity should be included. This would provide valuable information regarding the likelihood of other executive dysfunction and would allow a more targeted assessment approach by limiting the more extensive testing of executive functions to only those people whose comparatively lower working memory performance indicated that further problems may exist.

text: The effects of multiple sclerosis: Exploring executive dysfunction and its linkswith other cognitive impairment Multiple Sclerosis (MS) is one of the most common chronic diseases of the central nervous system, and in New Zealand an estimated 4,000 people are currently affected. Although the physical manifestations of the disease are well known, and memory impairments have been comparatively well researched, those cognitive abilities known collectively as executive functions, and their relationship with other cognitive processes, have seldom been examined.
To fill this research gap, the present study examined the extent and nature of executive dysfunction and other cognitive impairments in a community based sample of participants with MS, and explored any links between executive dysfunction and other cognitive processes. Due to the well known heterogeneous nature of the effects of MS, impairment was assessed not only for the sample as a whole, but more informatively, and in contrast to much of the previous research on MS, within smaller more homogeneous groups formed on the basis of the extent and nature of the cognitive impairment of the participants. As the behavioural characteristics of executive dysfunction may have an influence on the ability to function appropriately on a daily basis in the community at large, evidence of typical 'dysexecutive' behaviour was also examined.
Ninety five participants with MS were assessed on general ability (WAIS-III), memory (WMS-III), executive functioning (D.KEFS), information processing speed and simple attentional processes. While the extent of impairment remained low on general ability measures, some impairment became evident in over half of the participants with MS on the memory measures. Five categories of executive functioning were used to assess the extent and nature of executive dysfunction; Inhibition, Shifting, Reasoning, Planning and Fluency. Working memory was not included as an executive category, as the primary scores obtained from the D.KEFS assessment did not enable this process to be isolated. Working memory was however evaluated as part of the memory assessment (WMS - III). Over half the participants were found to be impaired in at least one category of executive dysfunction, and the most commonly impaired categories were fluency and reasoning. Although sixteen different profiles of executive dysfunction were evident amongst the participants, the majority of those impaired were assessed with only one category of impairment. Surprisingly, no impairment in information processing speed was evident, but some participants were impaired in relation to simple attentional processes. 
The participants with MS were subsequently divided into four groups based on the nature of their impairment, that is, depending on whether the participant had no impairment, memory impairment only, memory impairment and executive dysfunction or executive dysfunction only. The index scores for visual memory were found to be consistently lower than those for auditory memory for all the 'impairment type' groups, but little difference was found between long-term and short-term memory performance. Working memory was found to be the only cognitive process which differentiated between those groups with executive dysfunction and those without, and at all levels of performance, proved to be a reliable predictor of the degree of executive dysfunction. Working memory was also found to have a differing relationship with each of the other five specific categories of executive functioning. 
When the everyday behavioural characteristics of executive dysfunction, such as inhibition, intentionality, executive memory and positive and negative affect were assessed with the Dysexecutive Questionnaire, there was little evidence of any self reported problems. In particular, levels of insight were shown not to be compromised, therefore it seemed that if any behavioural difficulties did arise for the participants, they would have been able to recognize and subsequently address them. Thus, it appeared for this sample of participants with MS that although some executive dysfunction was more prevalent than had previously been suggested in the literature on MS, generally the living arrangements of these participants seemed appropriate in relation to their ability to function independently. 
Overall, it was recommended that for the initial cognitive assessment of those with MS, a comprehensive evaluation of working memory integrity should be included. This would provide valuable information regarding the likelihood of other executive dysfunction and would allow a more targeted assessment approach by limiting the more extensive testing of executive functions to only those people whose comparatively lower working memory performance indicated that further problems may exist.

year: 2005

title: Stemming the colonial environmental tide

authors: Joseph, Robert

subjects: human activities

abstract: Stemming the colonial environmental tide supports an Aotearoa New Zealand context that fundamentally acknowledges mātauranga and tikanga Māori law and shared co-governance and concurrent jurisdiction through 7 Aotearoa New Zealand EBM principles.

text: Stemming the colonial environmental tide Stemming the colonial environmental tide supports an Aotearoa New Zealand context that fundamentally acknowledges mātauranga and tikanga Māori law and shared co-governance and concurrent jurisdiction through 7 Aotearoa New Zealand EBM principles.

year: 2022-05