471 research outputs found
Use of High Resolution Melting for Genotyping Leptospira spp.
No full textBackground
Leptospirosis is a worldwide zoonosis that is endemic in tropical areas. The species Leptospira interrogans is the primary agent in human infections, but other pathogenic species, such as L. kirschner and L. borgpetersenii, are also associated with human leptospirosis.
Methods and Findings
In this study, an unsupervised high resolution melting (HRM) analysis of the products that were amplified with five pairs of primers lfb1 F/R, G1/G2, VNTR-4Bis, VNTR-Lb4 and VNTR-Lb5 facilitated an accurate species classfication of Leptospira reference strains from New Caledonia Institute Pastéur. Next, the genotypes at the subspecies level was identificated by using method with LightCycler®480 instrument and the High Resolution Melting Master kit (04909631001). LightCycler®480 Gene Scanning Software was used to perform a futher analysis results.
Conclusions
This new HRM method enabled the identification of Leptospira strains at the species and subspecies levels and support the direct genotyping of Leptospira in biological samples without requiring cultures
Use of high resolution melting for genotyping Leptospira spp.
No full textBackground
Leptospirosis is a worldwide zoonosis that is endemic in tropical areas. The species Leptospira interrogans is the primary agent in human infections, but other pathogenic species, such as L. kirschner and L. borgpetersenii, are also associated with human leptospirosis.
Methods and Findings
In this study, an unsupervised high resolution melting (HRM) analysis of the products that were amplified with five pairs of primers lfb1 F/R, G1/G2, VNTR-4Bis, VNTR-Lb4 and VNTR-Lb5 facilitated an accurate species classfication of Leptospira reference strains from New Caledonia Institute Pastéur. Next, the genotypes at the subspecies level was identificated by using method with LightCycler®480 instrument and the High Resolution Melting Master kit (04909631001). LightCycler®480 Gene Scanning Software was used to perform a futher analysis results.
Conclusions
This new HRM method enabled the identification of Leptospira strains at the species and subspecies levels and support the direct genotyping of Leptospira in biological samples without requiring cultures
To Determine the Validity of the Sebia HbA1c Assay for Identifying Variant Haemoglobin Disorders
No full textThe purpose of this research is to determine if the Sebia HbA1c programme can be used to accurately identify patients with a variant haemoglobin chain. While this method is not currently validated as a diagnostic test for haemoglobin variants, it is a validated diagnostic test for diagnosing diabetes through the measurement of HbA1c. HbA1c testing is already part of the prenatal screening service to assess the risk of gestational diabetes in the Waikato and Bay of Plenty regions in New Zealand. However, as it is not a diagnostic test for variant haemoglobin detection, when an abnormal peak is detected, it is up to the clinician to order further tests to accurately identify the abnormal haemoglobin chain, resulting in increased costs and turnaround times for results. The only current diagnostic test is the Sebia Haemoglobin E method.
Data used in this study were from routine requests for haemoglobinopathy identification using the Sebia Haemoglobin E programme. These samples were run in parallel with the Sebia HbA1c programme to determine the difference between migration patterns and quantitation of haemoglobin peaks between both methods.
The results of this study demonstrate a good correlation between the two methods with a correlation coefficient of at least 0.9, however the HbA1c method shows a negative bias when compared to the reference method: the Haemoglobin E method. Despite this, laboratories could use the HbA1c technique as a presumptive method for identifying abnormal haemoglobin chains, provided adjustments to the reference intervals were made
Prevalence of Soil-Transmitted Helminthiasis in Central Eastern Division, Fiji Islands
No full textSoil-transmitted Helminthiasis (STH) affects approximately 1.5 billion people annually, 450 million of whom become ill as a result of infection. The World Health Organisation has labelled STH as a major neglected tropical disease (NTD). STH infections are caused by roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura), hookworms (Ancylostoma duodenale and Necator americanus) and threadworm (Strongyloides stercoralis) which are transmitted to humans by ingestion of infective eggs or contact with larvae. Fiji has inadequate data on the health status of STH. Insensitive laboratory diagnostic techniques suggest limitation exists in positive detection and cases maybe under-reported. There is no published data on STH infection and its association with NTDs, which limits information on trends relating to morbidity and efficacy of helminth control programmes.
The purpose of this research was to determine if the reference diagnostic laboratory at Colonial War Memorial Hospital (CWMH) in Suva, Fiji was using a sensitive and accurate STH examination technique. The major objectives of the research were to: (1) determine the prevalence of the soil-transmitted helminths diagnosed at CWMH in Central Eastern Division from January 2008 to December 2016 according to data retrieved from the laboratory register; (2) identify the current laboratory techniques used in diagnosing STH in Fiji and compare these with current recommended methods; and (3) provide recommendations to medical laboratories and the Fiji Ministry of Health to improve STH diagnosis.
Results from data analysis showed that from the total of 12,020 stool sample results retrieved 2.2% (n=261; 95% CI: 1.4-2.9) were positive for at least one STH parasite. A. lumbricoides contributed to most STH infections (68.7%), followed by hookworm (22.2%), S. stercoralis (8.0%) and T. trichiura (1.1%). The highest prevalence of STH was found in the < 5 year age group (33%). More samples from male patients had STH positive results (61%) compared to females at 101/261 (39%). In regards to ethnic groups, a higher proportion of i-Taukei population had helminth infections (93%) compared to Indo-Fijians (6%) and other races (1%). According to gender distribution, male i-Taukei individuals are mostly infected (48.4%), followed by female i-Taukei (33.5%), the Indo-Fijian females (4.7%) and Indo-Fijian males (2.2%), while other races were the least infected (0.4%).
Fiji still depends on direct microscopy and is lacking behind in STH diagnosis according to the updated WHO helminth testing standards. For STH diagnosis, the Kato-Katz (K-K) technique has been recommended by WHO as the gold-standard. The qPCR technique is an emerging molecular diagnostic technology and is considered superior to the K-K technique, due to its increased sensitivity and specificity. However, the higher costs involved in processing samples and the need for specialist technical staff could affect its implementation.
The prevalence study provides important epidemiological data of the STH parasites in the Central Eastern Division in Fiji. Socioeconomic factors, improper hygiene practices, climate change, rural-urban migration and remoteness could contribute towards STH infections. The K-K technique has been recommended by the WHO as the -gold-standard- for STH diagnosis in medical laboratories and should be implemented to diagnose STH in Central Eastern Division in Fiji. For future potential investigations of helminth infections, sustainable evaluation of parasite characteristics should be investigated for effectiveness of control factors
Prevalence of Soil-transmitted Helminthiasis in Central Eastern Division, Fiji Islands
No full textSoil-transmitted Helminthiasis (STH) affects approximately 1.5 billion people annually, 450 million of whom become ill as a result of infection. The World Health Organisation has labelled STH as a major neglected tropical disease (NTD). STH infections are caused by roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura), hookworms (Ancylostoma duodenale and Necator americanus) and threadworm (Strongyloides stercoralis) which are transmitted to humans by ingestion of infective eggs or contact with larvae. Fiji has inadequate data on the health status of STH. Insensitive laboratory diagnostic techniques suggest limitation exists in positive detection and cases maybe under-reported. There is no published data on STH infection and its association with NTDs, which limits information on trends relating to morbidity and efficacy of helminth control programmes.
The purpose of this research was to determine if the reference diagnostic laboratory at Colonial War Memorial Hospital (CWMH) in Suva, Fiji was using a sensitive and accurate STH examination technique. The major objectives of the research were to: (1) determine the prevalence of the soil-transmitted helminths diagnosed at CWMH in Central Eastern Division from January 2008 to December 2016 according to data retrieved from the laboratory register; (2) identify the current laboratory techniques used in diagnosing STH in Fiji and compare these with current recommended methods; and (3) provide recommendations to medical laboratories and the Fiji Ministry of Health to improve STH diagnosis.
Results from data analysis showed that from the total of 12,020 stool sample results retrieved 2.2% (n=261; 95% CI: 1.4-2.9) were positive for at least one STH parasite. A. lumbricoides contributed to most STH infections (68.7%), followed by hookworm (22.2%), S. stercoralis (8.0%) and T. trichiura (1.1%). The highest prevalence of STH was found in the < 5 year age group (33%). More samples from male patients had STH positive results (61%) compared to females at 101/261 (39%). In regards to ethnic groups, a higher proportion of i-Taukei population had helminth infections (93%) compared to Indo-Fijians (6%) and other races (1%). According to gender distribution, male i-Taukei individuals are mostly infected (48.4%), followed by female i-Taukei (33.5%), the Indo-Fijian females (4.7%) and Indo-Fijian males (2.2%), while other races were the least infected (0.4%).
Fiji still depends on direct microscopy and is lacking behind in STH diagnosis according to the updated WHO helminth testing standards. For STH diagnosis, the Kato-Katz (K-K) technique has been recommended by WHO as the gold-standard. The qPCR technique is an emerging molecular diagnostic technology and is considered superior to the K-K technique, due to its increased sensitivity and specificity. However, the higher costs involved in processing samples and the need for specialist technical staff could affect its implementation.
The prevalence study provides important epidemiological data of the STH parasites in the Central Eastern Division in Fiji. Socioeconomic factors, improper hygiene practices, climate change, rural-urban migration and remoteness could contribute towards STH infections. The K-K technique has been recommended by the WHO as the -gold-standard- for STH diagnosis in medical laboratories and should be implemented to diagnose STH in Central Eastern Division in Fiji. For future potential investigations of helminth infections, sustainable evaluation of parasite characteristics should be investigated for effectiveness of control factors
The User Experience of an Online Platform When Learning Cytology
No full textThis research addresses the user experience of an online platform when learning cytology. The study was based in Auckland and the investigation undertaken involved three stages. The first stage was with the student community enrolled in an undergraduate level histology/cytology course of Bachelor of Medical Laboratory Science at Auckland University of Technology. The aim was to explore the students’ experiences of the cytology platform www.cytologystuff.com. The second stage was with the cytotechnologist community working at Diagnostic Medlab. The aim was to explore the users’ perceived convenience, its values as a learning tool, and their perception of being a peripheral member of a virtual community of practice that might also be advantageous to students. The last stage was a self-reflection that explores the researcher’s personal experience. The aim was to explore the use of the online platform, providing a reflective account of the researchers’ experience and barriers encountered. The study involved undertaking a qualitative and quantitative piece of research.
Mixed methods approach, taken included an open-end and closed-end questionnaire to provide the data. The student survey cohort was collected online through www.surveymonkey.com. The cytotechnologist survey was paper based, as this was identified as being more appropriate by the staff manager. Participants’ responses were then transferred to www.surveymonkey.com, to assist in the data analysis process; the research methods, survey questionnaire and data finding are in chapter four.
Actor-Network Theory provides a framework to analyse user experience of an online platform for learning cytology, with accounts of what students, cytotechnologist staff and researchers experience when making use of the online platform www.cytologystuff.com.
What this site might provide an opportunity for students to be involved in an online community of practice was investigated. However, the data analysed using the study simple statistical analysis methods showed mixed results. The analysis informed by Actor-Network Theory provides sensibilities brought forward particular limitations in making use of the site. The students’ experience of the site was overwhelmingly positive as a learning tool, but it was perceived as too simplistic for the cytotechnologists for practical applications
Metabolomics Applications in Immunological Studies of Marine Molluscs
No full textMolluscs form an important group in aquaculture as well as in coastal wild systems. However, high mortalities in molluscan species, specifically marine bivalves, have been encountered in the wild during summer times (summer mortality) as well as in aquaculture settings, which present a major economical challenge in many parts of the world. The complex interactions between host, environment and pathogens during these mortality events require new diagnostic tools and integrated approaches. Metabolomics is one of the newest and fastest growing omics. The sensitivity and specificity of metabolomics approaches make this a powerful tool for immunological studies, where it can provide insights into disease processes as well as the identification of metabolite biomarkers for early warning systems. This thesis was designed to provide, for the first time, a comprehensive understanding of the metabolic responses of mussel haemocytes and other tissues (e.g., gills, hepatopancreas, mantle) to external stimuli (Vibrio sp., lipopolysaccharides [LPS], Cu²⁺) using gas chromatography-mass spectrometry (GC-MS)-based metabolomics approach. Along with the core metabolomics tool, novel flow cytometry (FCM) protocols were developed in order to assess immunological parameters of the host upon stimulation. The combined method allows characterization of the mussel immune responses at both cellular and molecular levels and expands the number of biomarkers used to understand the animal’s response.
Initially, tissue-specific metabolic responses of gill, haemolymph and hepatopancreas were observed in mussels challenged with Vibrio sp. Then, haemolymph was chosen as the target tissue/organ for the rest of the experiments in the thesis (Chapter 4). FCM revealed sex-based differences in immune responses of mussels to Vibrio sp. challenge. In this case, female mussels had lower haemocyte mortality, production of reactive oxygen species (ROS) and apoptotic cells after pathogen exposure compared to male mussels (Chapter 5). This suggests that female mussels have more efficient defence system than male mussels. However, metabolite profiles of haemolymph showed no significant difference between males and females. Subsequently, metabolic profiles of mussel haemolymph were intensively investigated in response to Vibrio sp. challenge, LPS and copper exposure (Chapter 6, 7 & 8). The alterations of metabolite profiles along with changes in immune characteristics due to stimulation provided insights into a number of pathways involved in immune responses of the host to Vibrio sp. infection and copper exposure.
The study also identified a number of candidate biomarkers involved in mussel immune processes. Among these metabolites, the presence of itaconic acid (ITA) and its accumulation were observed in different tissues of mussels following Vibrio sp. challenges, suggesting the important role of this metabolite as an antimicrobial compound in the innate immune system of bivalves (Chapter 4, 5 & 6). In fact, the challenge experiment (Chapter 9) revealed the complete inhibition of ITA on Vibiro sp. growth at 6 mM, and Vibrio growth was partially inhibited at 3 mM ITA. This confirmed, for the first time, the antibacterial activity of ITA against marine Vibiro sp. and suggests that ITA could be used as an antimicrobial compound for antibiotic resistant bacteria in aquaculture. Subsequently, the ITA concentrations in different tissues of mussels challenged with Vibrio sp. were quantitatively measured (Chapter 10). Interestingly, the results revealed that mussels are able to produce an effective amount of ITA to support the internal defence system, suggesting that ITA could be a valuable biomarker for health assessment of bivalves. In addition, ITA may also involve in anti-inflammation activities and other unknown functions in the bivalve innate immune system, which need further studies to reveal.
In conclusion, this thesis has successfully demonstrated the use of novel metabolomics approaches for aquaculture and marine science, which contribute new information regarding the molluscan immune system. It is envisaged that metabolomics will continue to grow as a tool of choice in studies of marine molluscs, as well as the broader field of marine science
Immunological and Metabolomics Tools for Health Assessment of Farmed New Zealand Chinook Salmon (Oncorhynchus tshawytscha)
No full textNew Zealand’s Chinook salmon (Oncorhynchus tshawytscha) farming started in 1976 and has developed to become the number one farmed finfish in the country. New Zealand is the leading global producer and supplier of farmed O. tshawytscha. New Zealand’s O. tshawytscha production remains free from diseases that have devastated global salmon farming (Diggles, 2016). However, the recent emergence of New Zealand rickettsia-like organism (NZ-RLO) (Brosnahan et al., 2017), continued industry growth, and climate change, necessitates the development of health assessment tools. The aim of this thesis was to develop immunological and metabolomic tools for farmed O. tshawytscha health assessment.
Farmed O. tshawytscha peripheral blood was characterised for cellular composition and a micro-volume blood technique was developed for isolation of fish peripheral blood mononuclear cells (PBMCs) using Lymphoprep. Differential cell counts identified five cell types including erythrocytes, lymphocytes, thrombocytes, monocytes and unquantifiable neutrophils, important in future health assessments. Isolated PBMCs enable field on-farm sampling for longitudinal studies and allow in vitro immunological assessments. Findings provided the possibility to make fish health assessments in the field without fish euthanisation.
The developed micro-volume blood technique was used to isolate O. tshawytscha PBMCs. These PBMCs were used to model the functional and targeted immune cytokine responses to Gram-negative bacterial lipopolysaccharide (LPS) from Escherichia coli in vitro. Bacterial LPS stimulated biphasic reactive oxygen species (ROS) production enhanced by interferon (ifn) inducible cytokines, and phagocytosis. LPS also upregulated pro-inflammatory interferon gamma (ifnγ), tumour necrosis factor alpha (tnf-α), and anti-inflammatory interleukin-10 (il-10) 24 h post-stimulus. This provided the first report of LPS induced immunomodulation in O. tshawytscha in vitro. The results have high application potential in modelling response mechanisms to emerging NZ-RLO pathogenesis.
The response mechanisms of O. tshawytscha to polyinosinic: polycytidylic acid [poly (I:C)] were investigated 24 h post-in vivo stimulation. The most striking results were observed at the metabolomic level. Poly (I:C) upregulated metabolites involved in branched‐chain amino acid (BCAA)/glutathione and transsulphuration pathways and phospholipid metabolism, while those involved in energy metabolism were downregulated. At the molecular level, poly (I:C) enhanced antiviral ifnγ in head kidney (HK) and Mx1 protein in head kidney (HK), spleen (SP) and red blood cells (RBCs). Findings provide insights into poly (I:C) induced immune‐related biomarkers at metabolic and molecular levels important in future investigations.
The effects of poly (I:C) in vivo on O. tshawytscha haematology, innate immunity, serum and liver metabolite profiles, HK, and SP cytokine transcript expression, over a 5-day period post-injection were studied. Important responses included enhanced neutrophil counts and PBMC ROS production. Metabolically, poly (I:C) upregulated liver and serum metabolites involved in BCAA at day one and returned to normal by day five, while metabolites involved in glycolysis were persistently depleted. Metabolic results suggest that poly (I:C) induced response mechanisms similar to those observed in viral-infected fish, where the host metabolome is hijacked to favour viral replication. At the molecular level, poly (I:C) promoted antiviral ifnγ and Mx1, and anti-inflammatory il-10 in fish lymphoid organs, depict O. tshawytscha immune defence against infection. Results may act as a primer for developing amelioration strategies against viral infections in aquaculture.
Finally, O. tshawytscha were subjected to a three-month thermal stress challenge (17°C vs 19°C-20°C) to identify blood biomarkers of thermal tolerance and growth performance (weight loss vs weight gain). Independent of growth performance, thermal stress induced leucocyte apoptosis, minor immune responses, and disturbed plasma osmoregulation via reduced Na+/K+-ATPase activity. Irrespective of culture temperature, fish that lost weight were characterised by several biomarker alterations in cellular haematology and plasma clinical chemistries suggestive of suppressed feed intake. Findings provide insights into physiological and growth effects of thermal stress on O. tshawytscha, useful in selective breeding strategies.
Overall, depending on resource availability, this thesis has demonstrated the usage of classical haematology, novel flow cytometry, molecular and metabolomic tools in farmed O. tshawytscha health assessment. The thesis thus recommends an integrated approach of classical assays with the more recent flow cytometry and metabolomics approaches to promote holistic farmed teleost health assessments.
Keywords
Farmed Salmon; Aquaculture; Oncorhynchus tshawytscha; Metabolomics; Immunology; Flow Cytometry; Peripheral Blood Mononuclear Cells; Haematology; Biomarker
In Vitro Study of the Cytotoxic Effects of Low- and High-molecular-weight Fucoidan Extracted from New Zealand Seaweed Undaria Pinnatifida in MCF-7 and MDA-MB-231 Breast Cancer Cell Lines
No full textBreast cancer is known as the top cancer for women worldwide. It is estimated that every year over one million new cases of breast cancer are diagnosed and contribute largely to cancer related deaths. Chemotherapy, including neoadjuvant therapy and adjuvant therapy, is a critical part in treatment for breast cancer that impact on survival and life quality for patients. However, chemo-resistance and adverse effects occur frequently when patients receive chemotherapy or the improved target therapies. New strategies have been proposed to enhance the effects of anticancer drugs as combing them with natural dietary compounds, decreasing drug dose administered and reducing the toxicity to normal cells.
Fucoidan is noticed for its anti-cancer potential in treating breast cancer as well as in many other cancers. It is a natural bioactive compound derived from brown algae that has low toxicity and multiple anti-cancer pathways, the potential of which makes it a candidate for therapeutic agent using alone or in combination with other cytotoxic drugs. Base on the molecular weight, fucoidan can be categorised into three ranges: high-molecular weight fucoidan (HMF, >300k), medium-molecular weight fucoidan (MMF, 300-10k) and low-molecular weight fucoidan (LMF, <10k). In this study, the inhibitory effects of HMF and LMF from New Zealand Undaria Pinnatifida have been studied against breast cancer. Two breast cancer cell lines, MCF-7 and MDA-MB-231, have been used in this study representing ER-positive type and triple-negative type of breast cancer. A fibroblast (HDFa) cell line has also been used in this study, representing non-cancer cells, to examine toxicity of fucoidan.
By conducting MTT assays, apoptosis assay and other related mechanism assays on cancer cells, the findings in this study indicate that LMF exhibited much better inhibition on proliferation of breast cancer cells than HMF. Dose-dependent inhibition by LMF was observed in both MCF-7 and MDA-MB-231 after incubated for 48, 72 and 96 hours. MCF-7 cells are more sensitive to LMF than MDA-MB-231 by a distinction of about 20% inhibition at the highest concentration of LMF (56.6% inhibition at 200 µg/ml and 39.2% inhibition at 300µg/ml,72hrs, respectively) and time-dependent manner of inhibition was only observed in MCF-7. The IC50 of LMF to MCF-7 cells over 72 hours was determined to be about 19 µg/ml and dropped to 10.5 µg/ml after 96 hours. Induction of caspase-dependent apoptosis was observed in MDA-MB-231 cells through intrinsic apoptosis pathway alone or with the extrinsic pathway. An activation of NOS stimulated by LMF was observed in MDA-MB-231 cells at a dose-dependent manner. No obvious cytotoxicity of LMF to HDFa cells was observed by 72 hours incubation in a cell cycle assay. To conclude, LMF from New Zealand Undaria Pinnatifida showed great anti-cancer effects against these two types of breast cancer, therefore, it has great potential to be used as a therapeutic agent or a supplement to combine with other chemo-agents for treating breast cancer, even though it may not be potent enough to treat this type of cancer alone
The Effect of Nutritional Ketosis on Performance and Immune Function in Endurance Athletes
No full textProlonged (>90 min), strenuous exercise depletes endogenous carbohydrate (CHO) stores and is associated with a transient state of immunodepression and increased illness risk. Commencing exercise with low CHO availability accelerates fatigue and exacerbates perturbations to several in vitro immune components, particularly inflammatory T-lymphocyte (T-cell) cytokine production to an immune challenge (i.e. stimulation). Recurrent illness impairs training availability and performance; therefore, CHO fuelling strategies are recommended to support both endurance performance and immune function. Ketone bodies are an additional energetic substrate derived exogenously via ingesting ketone or ketogenic supplements or endogenously via hepatic ketogenesis following conformity to a very low-CHO, ketogenic diet (KD). Ketone supplementation and adaptation to a KD increase blood KB concentrations (minutes vs. days to weeks, respectively) from 0.1-0.2 to >0.5 mmol/L (i.e. nutritional ketosis or hyperketonaemia); albeit, exert disparate effects on CHO and fat metabolism. Therefore, the aim of this thesis was to examine the effect nutritional ketosis – via exogenous and endogenous origin – on endurance performance and immune function.
To identify the optimal dose of the racemic ketogenic supplement, R,S-1,3-butanediol (BD), the first experiment (Chapter 4) explored dose response effects (0 + 0 g/kg; 0.5 + 0 g/kg; 0.7 + 0 g/kg; 0.35 + 0.35 g/kg BD; boluses separated by 1.5 h) on blood D--hydroxybutyrate (D-bHB) concentration and T-cell related interleukin (IL)-4, IL-10 and interferon (IFN)-g gene expression within Staphylococcal Enterotoxin B (SEB)-stimulated peripheral blood mononuclear cells (PBMC) at rest. BD ingestion increased blood D-bHB concentration up to ~1 mmol/L; however, there was no was no effect on T-cell related cytokine gene expression within SEB-stimulated PBMCs compared to placebo (PLA). The second (Chapter 5) and third (Chapter 6) experiments examined the effect of BD ingestion compared to PLA on a preloaded (85 min at 85% second ventilatory threshold) ~30 min cycling time-trial (TT) performance and T-cell related IL-4, IL-10 and IFN-g gene expression within SEB-stimulated PBMCs, respectively. BD ingestion increased blood D-bHB concentration to 0.4-0.8 mmol/L during exercise and 1.38 ± 0.35 mmol/L at 1-h post-TT; however, blood glucose and lactate concentrations, exercise efficiency (i.e. oxygen uptake) and TT performance were unaltered (PLA, 28.50 ± 3.59; BD, 28.72 ± 3.23 min), with participants reporting gastrointestinal distress and minor symptoms of nausea, euphoria and dizziness. BD ingestion increased T-cell related gene expression throughout the trial; whereas, IL-4 and IL-10 gene expression were unaltered. These findings suggest blood D-bHB concentrations up to ~1 mmol/L do not benefit high-intensity endurance performance, but may transiently amplify the initiation of a pro-inflammatory type-1 T-cell cytokine response to an immune challenge during and 1-h following exercise.
The fourth (Chapter 7) and fifth (Chapter 8) experiments examined the effect of a 31-day KD (13.7 MJ, 4% [0.5 g/kg/day] CHO and 78% [4 g/kg/day] fat) compared to the participants habitual, mixed diet (13.1 MJ, 43% [4.6 g/kg/day] CHO and 38% [1.8 g/kg/day] fat) on moderate-intensity (70% maximal oxygen uptake [VO2max]) running capacity and T-cell related IL-4, IL-10 and IFN-g gene expression within multi-antigen-stimulated PBMCs and salivary secretory immunoglobulin A (SIgA), respectively. Adaptation to the KD increased fat oxidation (2- to 3-fold) and blood D-bHB concentration to 0.6-1.6 mmol/L during exercise and 2.8 mmol/L at 1-h post-exhaustion, whilst reducing CHO oxidation. Despite impairing exercise efficiency, as evidenced by increased oxygen uptake and energy expenditure, mean time-to-exhaustion was unaffected following the KD (pre-HD, 237 ± 44 vs. post-HD, 231 ± 35 min; pre-KD, 239 ± 27 vs. post-KD, 219 ± 53 min). T-cell related IFN-g gene expression transiently increased immediately after exhaustion; whereas, IL-4 and IL-10 gene expression were unaltered following the KD. Diet and exercise had no effect on SIgA concentration and secretion rate. These findings suggest conforming to a KD can preserve submaximal exercise capacity and may transiently amplify the initiation of a pro-inflammatory type-1 T-cell cytokine response to an immune challenge immediately following exercise; however, it does not alter mucosal immunity.
In conclusion, the findings of this thesis demonstrate the unique effects of ketone supplementation and adaptation to a KD on exercise metabolism, endurance performance and immune function. BD ingestion does not improve high-intensity endurance performance and should be avoided due to adverse gastrointestinal and systemic effects. Whereas, adaptation to a KD can preserve submaximal exercise capacity and may be considered a viable dietary option for select individuals. Moreover, elevated blood D-HB concentration – via BD ingestion and adaptation to a KD – can transiently increase pro-inflammatory circulatory type-1 T-cell cytokine gene expression to an immune challenge following exercise onset and cessation; however, the clinical implications for immune function are uncertain
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