Добірка наукової літератури з теми "3205 Medical biochemistry and metabolomics"

Abstract BACKGROUND Metabolomics, the systematic analysis of low molecular weight biochemical compounds in a biological specimen, has been increasingly applied to biomarker discovery. CONTENT Because no single analytical method can accommodate the chemical diversity of the entire metabolome, various methods such as nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) have been employed, with the latter coupled to an array of separation techniques including gas and liquid chromatography. Whereas NMR can provide structural information and absolute quantification for select metabolites without the use of exogenous standards, MS tends to have much higher analytical sensitivity, enabling broader surveys of the metabolome. Both NMR and MS can be used to characterize metabolite data either in a targeted manner or in a nontargeted, pattern-recognition manner. In addition to technical considerations, careful sample selection and study design are important to minimize potential confounding influences on the metabolome, including diet, medications, and comorbitidies. To this end, metabolite profiling has been applied to human biomarker discovery in small-scale interventions, in which individuals are extremely well phenotyped and able to serve as their own biological controls, as well as in larger epidemiological cohorts. Understanding how metabolites relate to each other and to established risk markers for diseases such as diabetes and renal failure will be important in evaluating the potential value of these metabolites as clinically useful biomarkers. SUMMARY Applied to both experimental and epidemiological study designs, metabolite profiling has begun to highlight the breadth metabolic disturbances that accompany human disease. Experimental work in model systems and integration with other functional genomic approaches will be required to establish a causal link between select biomarkers and disease pathogenesis.

Abstract BACKGROUND Nutritional metabolomics is rapidly evolving to integrate nutrition with complex metabolomics data to discover new biomarkers of nutritional exposure and status. CONTENT The purpose of this review is to provide a broad overview of the measurement techniques, study designs, and statistical approaches used in nutrition metabolomics, as well as to describe the current knowledge from epidemiologic studies identifying metabolite profiles associated with the intake of individual nutrients, foods, and dietary patterns. SUMMARY A wide range of technologies, databases, and computational tools are available to integrate nutritional metabolomics with dietary and phenotypic information. Biomarkers identified with the use of high-throughput metabolomics techniques include amino acids, acylcarnitines, carbohydrates, bile acids, purine and pyrimidine metabolites, and lipid classes. The most extensively studied food groups include fruits, vegetables, meat, fish, bread, whole grain cereals, nuts, wine, coffee, tea, cocoa, and chocolate. We identified 16 studies that evaluated metabolite signatures associated with dietary patterns. Dietary patterns examined included vegetarian and lactovegetarian diets, omnivorous diet, Western dietary patterns, prudent dietary patterns, Nordic diet, and Mediterranean diet. Although many metabolite biomarkers of individual foods and dietary patterns have been identified, those biomarkers may not be sensitive or specific to dietary intakes. Some biomarkers represent short-term intakes rather than long-term dietary habits. Nonetheless, nutritional metabolomics holds promise for the development of a robust and unbiased strategy for measuring diet. Still, this technology is intended to be complementary, rather than a replacement, to traditional well-validated dietary assessment methods such as food frequency questionnaires that can measure usual diet, the most relevant exposure in nutritional epidemiologic studies.

AbstractThe goal of advancing science in health care is to provide high quality treatment and therapeutic opportunities to patients in need. This is especially true in precision medicine, wherein the ultimate goal is to link disease phenotypes to targeted treatments and novel therapeutics at the scale of an individual. With the advent of -omics technologies, such as genomics, proteomics, microbiome, among others, the metabolome is of wider and immediate interest for its important role in metabolic regulation. The metabolome, of course, comes with its own questions regarding technological challenges. In this opinion article, I attempt to interrogate some of the main challenges associated with individualized metabolomics, and available opportunities in the context of its clinical application. Some questions this article addresses and attempts to find answers for are: Can a personal metabolome (n = 1) be inexpensive, affordable and informative enough (i.e. provide predictive yet validated biomarkers) to represent the entirety of a population? How can a personal metabolome complement advances in other -omics areas and the use of monitoring devices, which occupy our personal space?

The rapid rise in obesity prevalence appears to be a reflection of the changes in dietary and behavioural patterns, with eating habits shifting to higher consumption of energy-dense foods which are rich in fats and sugars, while at the same time, levels of physical activity are decreasing. These differences in energy intake and expenditure, often referred to as energy balance, have direct implications for weight regulation, with even small deviations in daily energy balance resulting in large body weight changes over the long term. Diet and exercise interventions aiming to shift the energy balance towards negative by either decreasing caloric intake and/or increasing physical activity have shown to be effective for weight loss. Many iterations of such dietary and physical activity interventions have been proposed, but intermittent fasting (IF) and high intensity interval training (HIIT) have recently been purported as effective strategies. Despite their effectiveness, the molecular mechanisms by which these lifestyle interventions induce their effects are unclear. Therefore, the purpose of this thesis was to examine the effects of IF and HIIT, alone and in combination, on anthropometric and metabolic health parameters in a model of diet-induced obese mice. To elucidate possible mechanisms of action, we investigated the impact of both lifestyle interventions on mRNA-miRNA regulatory networks, but more importantly, how such changes may translate into exercise- induced and diet-induced improvements in body composition and metabolic health. The findings from the thesis demonstrate that intermittent fasting with or without high intensity interval training resulted in significantly less weight gain in male mice despite concurrently consuming a high fat and sugar diet. The reduced weight gain was predominantly in the form of lower fat mass accumulation, with no significant loss in lean mass. These observations were supported by enhanced expression of adipose tissue genes relating to fragmentation of unilocular lipid droplets, lipolysis, fatty acid oxidation and efflux. Moreover, lower expression levels of leptin, pro-inflammatory markers and markers of hypoxia were also observed. These changes were also reflected by changes in miRNA-24, -222, -145 and -143. Within the skeletal muscle, the combination of diet and exercise demonstrated minimal impact on mRNA and miRNA expression markers relating to energy metabolism, however IF alone displayed significantly lower expression of all markers compared to control mice or other intervention groups. Interestingly, the changes in body composition, glycaemic control, lipid panels and expression of mRNA and miRNA seem to be gender specific with different responses, independent of intervention, demonstrated in male mice compared to the female mice. In conclusion, the novel results from this thesis have demonstrated superior effects on body composition and lipid profiles following combined IF and HIIT compared to either diet or exercise intervention alone while concurrently consuming a high fat and sugar diet. These observations are likely due to the physiological and biochemical changes that occur within the adipose and skeletal muscle tissue when creating a negative energy balance shift. The gender specific responses to the same diet and/or exercise intervention could indicate potential hormonal differences influencing metabolic control/adaptation in mice. Identification of important regulatory miRNAs through this thesis could provide potential therapeutic targets for obesity treatment and management.

The investigations described in this thesis were prompted by an overall interest in the phenomenon of Troponin C (TnC) polymorphism in mammalian skeletal muscle. Gaining insights into this area of inquiry has been limited, in large part due to methodological problems associated with the identification of rat (a commonly used animal model for studying mammalian skeletal muscle) TnC isoforms on SDS gels. Therefore, a method was devised for unambiguous identification of TnC isoforms in rat single muscle fibres. This method, validated using rat skeletal muscle TnC isoforms purified for the first time as part of this study, was used in conjunction with myosin heavy chain (MHC) isoform based fibre-typing and Sr2+ -activation measurements to explore the relationship between MHC and TnC isoform composition in mammalian skeletal muscle at the single fibre level, and to revisit the controversial issue of the relationship between TnC isoform composition and fibre-type differences with respect to Sr2+ -activation characteristics.

Duchenne muscular dystrophy (DMD) is a lethal X-linked genetic disorder which results in chronic degeneration of skeletal muscle, significantly impacting on the duration and quality of life. Despite the genetic defect and the missing protein dystrophin having been identified and characterised over 20 years ago, curative genetic therapies are still not clinically applicable, and corticosteroids, which are the only significantly beneficial treatment option currently available to DMD patients, are associated with several side-effects. Thus, there is a need for additional therapeutic interventions that can improve skeletal muscle function and delay the onset of severe pathology in dystrophy. The amino acid taurine is essential for normal skeletal muscle function, and has been shown to act on several factors thought to be key contributors to the development of skeletal muscle pathology in dystrophy. Moreover, as dystrophic skeletal muscle demonstrates a significant decrease in taurine content, it is possible that raising intramuscular taurine stores may preserve muscle function in dystrophy, and thus have potential therapeutic applications. Despite this, only two studies have ever examined the effect of taurine supplementation on dystrophic muscle function. The purpose of this thesis was to examine the effect of taurine on dystrophic skeletal muscle function, which was performed in three studies using the dystrophic mdx mouse as a model for DMD.

Lipids and sodium (²³Na) are two essential components of the human body. They play a role in almost all biological systems. However, an increase in their levels is associated with metabolic diseases. The elevation of their contents can cause similar health disorders. Examples of prevalent disorders that share an increase of musculoskeletal lipids and ²³Na are hypertension and diabetes. However, the relationship between in vivo lipid and sodium levels in pathophysiology has not been studied enough and therefore is still unclear. Additionally, the available quantification methods to facilitate such a study may not be practical. They are either invasive, not sensitive enough, or require an impractical measurement time.

Therefore, in this work, our aims were to develop practical in vivo methods to quantify the absolute sodium concentration as well as the concentration of each lipid component individually, and to study the correlation between them within the skeletal muscles.

Since lipids and ²³Na have different nuclear magnetic resonance properties, their quantification by magnetic resonance (MR) techniques face different challenges. Thus, we optimized different MR spectroscopic imaging (MRSI) techniques for lipids and ²³Na.

Our proposed proton MRSI was able to provide eight lipid fat fraction (FF) maps representing each musculoskeletal lipid component (fatty acid) detected by our MRSI technique, and demonstrated a superior sensitivity compared to the conventional MR imaging methods.

For ²³Na, our developed ²³Na-MRSI was able to measure and map the absolute ²³Na concentration with values agreeing with those reported previously in biopsy studies, and with a high repeatability (CV < 6 %) within significantly shorter acquisition time compared to other available techniques.

Finally, the ²³Na concentration and the fat fractions of each lipid component within healthy skeletal muscles were measured and correlated using our developed MRSI methods. Our findings suggest a positive regional relationship between ²³Na and lipids and negative correlation between ²³Na and BMI under healthy conditions.

Chronic heart failure (CHF) patients have poor exercise tolerance, which does not correlate with impaired central function. Consequently factors other than impaired cardiac function must contribute to the exercise intolerance. Maladaptations in skeletal muscle appear to be a likely reason for the limited exercise tolerance. In study I, exercise tolerance and skeletal muscle metabolism and morphology were examined in 17 CHF patients and eight healthy similarly aged sedentary control subjects. In Study II, thirteen CHF patients participated in a study on the effects of resistance training on exercise tolerance and skeletal muscle morphology and metabolism.

The overall objectives of this thesis were to assess the calcium absorption of calcium fortified soymilk (CFSM) compared to cows’ milk in post menopausal women, and to investigate ways of optimising the calcium bioavailability from commercially available CFSM. The project consisted of two parts: in vitro studies and the in vivo clinical studies.

Obesity kills more than 2.8 million people globally each year regardless of economic status or age. The endocannabinoid system is a widely distributed lipid signalling system that regulates appetite, fatty acid oxidation, glucose metabolism and inflammation. Adiponectin plays a protective role against metabolic disorders. Skeletal muscle plays a leading role in fatty acid oxidation and glucose metabolism. Activation of Cannabinoids in adipose tissue results in a decrease in adiponectin and an increase in inflammation causing ER stress. Blocking cannabinoids causes a decrease in inflammation and increase in adiponectin. This suggests a direct yet to be determined relationship between the Endocannabinoid system and adiponectin resistance, which was the focus of this candidature. Sprague Dawley rats were fed a HFD (22%) for 12 weeks to elicit DIO, then injected daily (IP) with CB1 Antagonist (AM251- 3mg/kg) for 6 wks. Animals were anesthetised, and skeletal muscles (Red /White fibre types) surgically removed. Skeletal muscle was immediately placed in organ bath (37C -95%O25%) with Adiponectin for 30 minutes. Plasma analysis determined that chronic CB1 Antagonism in these rats resulted in a significant reduction in food intake, weight reduction, a reduction in Peri-renal and brown adipose tissue weight, and a reduction in plasma leptin and Glucagon. There was an increase in inflammatory plasma cytokines (Il-1α, IL-2, Il-4, Il-5, Il-17α, Il-18, RANTES, IL12p70). Muscle analysis found that CB1 Antagonism on whole muscle resulted in no changes in mitochondrial markers. Incubation of the soleus muscle with adiponectin showed a significant decrease in AdipoR1 expression. There was a decrease in markers of fatty acid oxidation in white skeletal muscle Sprague Dawley rats were fed HFD (22%) for 12 weeks then injected daily (IP) with either CB2 Agonist (AM1241-3mg/kg or CB2 Antagonist (AM630- 0.3mg/kg) for 6 wks. Animals were anesthetised, and muscles (Red and White fibre types) were surgically removed. Muscle was placed in an organ bath (37C -95%O2-5%) with Adiponectin for 30 minutes. Plasma analysis determined that CB2 modulation resulted in an initial decrease in food intake. CB2 stimulation caused an increase in IL12p70 and a decrease in Leptin in plasma. CB2 Antagonism caused a decrease in plasma Leptin, GLP-1, Ghrelin. Muscle analysis showed that blocking CB2 caused an increase in mitochondrial activity in red fibres via elevated concentrations of citrate synthase. Adiponectin exposure resulted in CB2 agonism causing a down regulation of the mRNA expression of both AMPK and PGC1α in the Extensor Digitorum Longus muscle. Human skeletal muscle (rectus abdominus) were sourced from Obese and Diabetic individuals undergoing routine lap band surgery. Myotubes were treated for a 24-hour period with either CB1 antagonist (AM251), CB2 antagonist (AM630) in isolation or in combination with Adiponectin. Results showed significant increase of AdipoR2 in combination with Adiponectin in Diabetic tissue. Blocking CB2 caused an increase in both AdipoR1 and AdipoR2 expression in diabetic tissue. The results of this thesis are the first to support the hypothesis of synergistic mechanisms at play between Endocannabinoids and Adiponectin in the skeletal muscle of Obese and Diabetic skeletal muscle tissue.

Increasing numbers of Australians are playing the sport of basketball. The game's ability to be played both indoors and outdoors, and the international popularity of the game make it an appealing sport for people of all ages. With an impressive 198 countries affiliated with the International Basketball Federation and an incredible 100,000,000 (one hundred million) women throughout the world playing basketball, the position of women's basketball has never looked stronger. According to Basketball Australia, females constitute 50% of the registered basketball playing population in Australia with approximately 350,000 participants. Participation rates have doubled in the last seven years. One of the factors believed to have contributed to the growth in the number of women playing basketball in Australia, is the increased profile of the Women's National Basketball League (WNBL). According to Leanne Grantham, Chief Executive of the WNBL, record crowds were recorded throughout the 1995/96 seasons with a subsequent rise in the level of media interest. The WNBL was one of Australia's first full home and away sporting competitions for women and is considered to be one of the three most competitive female basketball competitions in the world. This is reflected in the high number of overseas players (imports) who seek to join the competition each year. Tom Maher, Head Coach of the Australian Senior Women's Basketball Team (Opals), advocates that the standard of the WNBL is in a large way responsible for the success of Australian Junior and Senior Teams at international competitions. The Australian Junior Women's Team (Gems) won a silver medal at the 1997 World Junior Championships and is currently ranked two in the World and the Senior Women's Team, which won its first ever Olympic medal (bronze) at the 1996 Atlanta Olympic Games, is currently ranked three. Given the increase in the profile of women's basketball both in Australia and overseas, it is interesting to note the limited number of studies which have investigated the physiological requirements of the game. A physiological investigation of elite women's basketball may provide answers to questions such as: What is the nature of the physiological strain incurred by elite players during performance? Which system does the majority of energy contribution during performance come from? What type of specific strength and conditioning is required? Do the physiological stresses placed on elite women basketballers vary according to position?

Cancer immunotherapy involves the manipulation of the immune response to combat tumour cells. The studies contained within investigated the role of cytokines in the anti-tumour immune response to the cancer antigen, MUCl, which is over produced in an altered form in cancers of the breast, pancreas, and ovary making an ideal target for immunotherapy. MUCl coupled to oxidised mannan (MFP), forms a powerful immunotherapeutic reagent capable of inducing tumour regression and cell mediated immune responses that protect against tumour challenge in many in vivo tumour models. This thesis characterised the Tl cytokine profile induced from CD8+ and CD4+ T cells following immunisation with MFP and suggested a role for IL-12 in the MUCl anti-tumour immune response. The addition of various combinations of Tl and T2 cytokines to MFP injections considerably increased the MUCl CTLp response, and demonstrated a role for IL-5 in the induction of cytotoxic T cells. A MUCl mammary carcinoma tumour was characterised to provide a more realistic model for MUCl immunotherapy studies. However, of particular significance was the discovery that additional IL-12 included in MFP immunisations,considerably decreases tumour growth in MUCl transgenic mice and significantly increases the MUCl specific CTLp response. The use of IL-12 and MFP in cancer immunotherapy has now progressed into Phase I human clinical trials in cancer patients.

The purpose of this study was to investigate the intensities of work and the patterns of play during men's basketball and, in addition, to investigate the exercise metabolism that meets the energy demands of participation. Eight (8) male basketball players participating in the 1992 National Basketball League (NBL) were monitored during practice games and Victorian Basketball Association games. Each subject was videoed during competition and had his HR monitored at 15 second intervals throughout the game. In addition, arterialised blood samples were obtained at various stages throughout the game and analysed for lactate concentration.