title: Establishing conversion of the 16-item Informant Questionnaire on Cognitive Decline in the Elderly scores into interval-level data across multiple samples using Rasch methodology

authors: Truong, Quoc Cuong

subjects: Informant Questionnaire on Cognitive Decline in the Elderly

abstract: BACKGROUND: The 16-item Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE-16) is a well-validated and widely-used measure of cognitive changes (CCs) among older adults. This study aimed to use Rasch methodology to establish psychometric properties of the IQCODE-16 and validate the existing ordinal-to-interval transformation algorithms across multiple large samples. 
METHODS: A Partial Credit Rasch model was employed to examine psychometric properties of the IQCODE-16 using data (n = 918) from two longitudinal studies of participants aged 57-99 years: the Older Australian Twins Study (n = 450) and the Canberra Longitudinal Study (n = 468), and reusing the Sydney Memory and Ageing Study (MAS) sample (n = 400). 
RESULTS: Initial analyses indicated good reliability for the IQCODE-16 (Person Separation Index range: 0.82-0.90). However, local dependency was identified between items, with several items showing misfit to the model. Replicating the existing Rasch solution could not reproduce the best Rasch model fit for all samples. Combining locally dependent items into three testlets resolved all misfit and local dependency issues and resulted in the best Rasch model fit for all samples with evidence of unidimensionality, strong reliability, and invariance across person factors. Accordingly, new ordinal-to-interval transformation algorithms were produced to convert the IQCODE-16 ordinal scores into interval data to improve the accuracy of its scores. 
CONCLUSIONS: The findings of this study support the reliability and validity of the IQCODE-16 in measuring CCs among older adults. New ordinal-to-interval conversion tables generated using samples from multiple independent datasets are more generalizable and can be used to enhance the precision of the IQCODE-16 without changing its original format. An easy-to-use converter has been made available for clinical and research use.

text: Establishing conversion of the 16-item Informant Questionnaire on Cognitive Decline in the Elderly scores into interval-level data across multiple samples using Rasch methodology BACKGROUND: The 16-item Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE-16) is a well-validated and widely-used measure of cognitive changes (CCs) among older adults. This study aimed to use Rasch methodology to establish psychometric properties of the IQCODE-16 and validate the existing ordinal-to-interval transformation algorithms across multiple large samples. 
METHODS: A Partial Credit Rasch model was employed to examine psychometric properties of the IQCODE-16 using data (n = 918) from two longitudinal studies of participants aged 57-99 years: the Older Australian Twins Study (n = 450) and the Canberra Longitudinal Study (n = 468), and reusing the Sydney Memory and Ageing Study (MAS) sample (n = 400). 
RESULTS: Initial analyses indicated good reliability for the IQCODE-16 (Person Separation Index range: 0.82-0.90). However, local dependency was identified between items, with several items showing misfit to the model. Replicating the existing Rasch solution could not reproduce the best Rasch model fit for all samples. Combining locally dependent items into three testlets resolved all misfit and local dependency issues and resulted in the best Rasch model fit for all samples with evidence of unidimensionality, strong reliability, and invariance across person factors. Accordingly, new ordinal-to-interval transformation algorithms were produced to convert the IQCODE-16 ordinal scores into interval data to improve the accuracy of its scores. 
CONCLUSIONS: The findings of this study support the reliability and validity of the IQCODE-16 in measuring CCs among older adults. New ordinal-to-interval conversion tables generated using samples from multiple independent datasets are more generalizable and can be used to enhance the precision of the IQCODE-16 without changing its original format. An easy-to-use converter has been made available for clinical and research use.

year: 2023-02-13

title: Molecular Characterisation of Sex Differentiation Genes in Yellowtail Kingfish (Seriola lalandi)

authors: Elliott, Nicholas B.

subjects: seriola

abstract: Species diversification is crucial for the successful establishment and growth of a finfish aquaculture industry in New Zealand. The yellowtail kingfish Seriola lalandi is a promising candidate species with a fast growth rate, high market value, and is successfully farmed overseas, along with several other Seriola species. To truly domesticate any farmed species, understanding reproduction is vital. Sexual differentiation is a key part of early reproductive development and is characterised by the migration of primordial germ cells through the body to the site of the presumptive gonad, where they proliferate and differentiate into spermatogonia and oogonia. A number of key genes are expressed during sex differentiation, but currently very little molecular research has been conducted on S. lalandi. 

Using bioinformatics approaches, the available gene databases and the implementation of a transcriptomic library prepared from the gonad, ovary and pituitary tissue of S. lalandi, a number of key sex differentiation genes were identified, which included, Vasa, Amh and Cyp19a1a. Primers were designed to each gene, to enable confirmation of the gene sequences, by PCR and RACE-PCR. Using this approach, no confirmed sequence was obtained for Cyp19a1a, however sequences were obtained for part of the Vasa gene and a large part of the Amh gene, including the 3’end. 

The availability of these sex differentiation gene sequences allowed expression of Vasa, Amh and Cyp19a1a to be investigated. Primers were designed using the confirmed sequences for Vasa and Amh, as well as the unconfirmed sequence for Cyp19a1a. These were used in real-time PCR to examine the expression of each gene during development, within larvae at hatching, 3 days post hatch (dph), 12 dph and 18 dph. Expression of each gene was found to increase by 12 dph, but then decrease at 18dph, however, no meaningful significant difference in expression was seen statistically between any of the time points.

Lastly, a protocol was developed for embedding and sectioning of larvae from a range of different ages. A number of attempts were made to optimise an approach, with fish from 3 dph to 60 dph eventually being paraffin embedded, sectioned and stained with either toluidine blue or hematoxylin and eosin (H&E). A number of regions of interest were described, with one showing good similarity to early gonad formation, detailed in other studies. However, due to technical issues and time constraints, no PGCs or presumptive gonad tissues could be positively identified. Future work will use prepared sections to stain for the sex differentiation genes, to gain a better understanding of their role during development. 

This study has established a platform for further work on S. lalandi by creating a framework of molecular tools for studying sex differentiation genes and their expression in this species. It has also worked towards refining the histological techniques required to successfully analyse structural development in larvae. This will be valuable for future studies with techniques such as in-situ hybridisation, assisting in the development of tools for the improvement of S. lalandi aquaculture, for applications such as monosex culture and surrogate broodstock technology.

text: Molecular Characterisation of Sex Differentiation Genes in Yellowtail Kingfish (Seriola lalandi) Species diversification is crucial for the successful establishment and growth of a finfish aquaculture industry in New Zealand. The yellowtail kingfish Seriola lalandi is a promising candidate species with a fast growth rate, high market value, and is successfully farmed overseas, along with several other Seriola species. To truly domesticate any farmed species, understanding reproduction is vital. Sexual differentiation is a key part of early reproductive development and is characterised by the migration of primordial germ cells through the body to the site of the presumptive gonad, where they proliferate and differentiate into spermatogonia and oogonia. A number of key genes are expressed during sex differentiation, but currently very little molecular research has been conducted on S. lalandi. 

Using bioinformatics approaches, the available gene databases and the implementation of a transcriptomic library prepared from the gonad, ovary and pituitary tissue of S. lalandi, a number of key sex differentiation genes were identified, which included, Vasa, Amh and Cyp19a1a. Primers were designed to each gene, to enable confirmation of the gene sequences, by PCR and RACE-PCR. Using this approach, no confirmed sequence was obtained for Cyp19a1a, however sequences were obtained for part of the Vasa gene and a large part of the Amh gene, including the 3’end. 

The availability of these sex differentiation gene sequences allowed expression of Vasa, Amh and Cyp19a1a to be investigated. Primers were designed using the confirmed sequences for Vasa and Amh, as well as the unconfirmed sequence for Cyp19a1a. These were used in real-time PCR to examine the expression of each gene during development, within larvae at hatching, 3 days post hatch (dph), 12 dph and 18 dph. Expression of each gene was found to increase by 12 dph, but then decrease at 18dph, however, no meaningful significant difference in expression was seen statistically between any of the time points.

Lastly, a protocol was developed for embedding and sectioning of larvae from a range of different ages. A number of attempts were made to optimise an approach, with fish from 3 dph to 60 dph eventually being paraffin embedded, sectioned and stained with either toluidine blue or hematoxylin and eosin (H&E). A number of regions of interest were described, with one showing good similarity to early gonad formation, detailed in other studies. However, due to technical issues and time constraints, no PGCs or presumptive gonad tissues could be positively identified. Future work will use prepared sections to stain for the sex differentiation genes, to gain a better understanding of their role during development. 

This study has established a platform for further work on S. lalandi by creating a framework of molecular tools for studying sex differentiation genes and their expression in this species. It has also worked towards refining the histological techniques required to successfully analyse structural development in larvae. This will be valuable for future studies with techniques such as in-situ hybridisation, assisting in the development of tools for the improvement of S. lalandi aquaculture, for applications such as monosex culture and surrogate broodstock technology.

year: 2015

title: Indigenous knowledge, methodology and mayhem: What is the role of methodology in producing indigenous insights? A discussion from Mātauranga Māori

authors: Smith, Linda Tuhiwai

abstract: The emergence of an academic discourse called Indigenous knowledge internationally, and mātauranga Māori in Aotearoa New Zealand, presents some substantive challenges to concepts of knowing and being, of knowledge creation, knowledge work and the making of meaning. These challenges engage us across philosophical, disciplinary, institutional, inter-generational, territorial and community boundaries, presenting an opportunity to imagine this field anew, and the theories and methodologies that inform contemporary Māori or Indigenous Studies. This article raises some discussion about ‘research methodologies’ being used when discussing mātauranga Māori and Indigenous knowledge (hereafter referred to as IK mātauranga). Research methodologies are often associated with specific disciplines of knowledge and viewed as the primary if not singular way in which knowledge is generated. Arguably, IK mātauranga occupies a different knowledge space from traditional academic disciplines, including their transdisciplinary interstices. This article speaks to a gnawing sense that mayhem is at play, as the academic work around IK mātauranga begins to consolidate and become institutionalised away from its indigenous communities and contexts, where it began and where it still informs identities, ways of living and being.

text: Indigenous knowledge, methodology and mayhem: What is the role of methodology in producing indigenous insights? A discussion from Mātauranga Māori The emergence of an academic discourse called Indigenous knowledge internationally, and mātauranga Māori in Aotearoa New Zealand, presents some substantive challenges to concepts of knowing and being, of knowledge creation, knowledge work and the making of meaning. These challenges engage us across philosophical, disciplinary, institutional, inter-generational, territorial and community boundaries, presenting an opportunity to imagine this field anew, and the theories and methodologies that inform contemporary Māori or Indigenous Studies. This article raises some discussion about ‘research methodologies’ being used when discussing mātauranga Māori and Indigenous knowledge (hereafter referred to as IK mātauranga). Research methodologies are often associated with specific disciplines of knowledge and viewed as the primary if not singular way in which knowledge is generated. Arguably, IK mātauranga occupies a different knowledge space from traditional academic disciplines, including their transdisciplinary interstices. This article speaks to a gnawing sense that mayhem is at play, as the academic work around IK mātauranga begins to consolidate and become institutionalised away from its indigenous communities and contexts, where it began and where it still informs identities, ways of living and being.

year: 2016