31 research outputs found
Metabolic variation in cultured cells treated with differentially functionalised gold nanoparticles (GNPs)
No full textMSc (Biochemistry), North-West University, Potchefstroom Campus, 2017Gold nanoparticles (GNPs) and differentially functionalised or ligand exchanged GNPs (Lig-GNPs) present promising advantages in a variety of fields. Surface functionalisation of GNPs with ligands is believed to improve the biocompatibility of the GNPs. However, the effects of these particles on biological systems remain unclear due to contradictions and several limitations in the literature, such as unstandardised protocols. Standardised methods and compatibility of assays with GNPs are essential in accurately determining the overall effect of GNPs on biological systems. Metabolomics analysis may present answers to the possible effects observed in the literature as it presents the metabolites, which are the closest to the functional phenotype of a biological system. However, research in these two fields as a combination is greatly limited. This study reveals the metabolic variation that occurs in HepG2 cells when treated with PVP-GNPs, PSSNa-GNPs and Citrate-GNPs by using standardised, pre-evaluated protocols. The results show that even though differentially functionalised GNPs seem to improve the biocompatibility of the particles, GNPs do induce variation on metabolome level; however, the variation is not necessarily linked with cytotoxicity. This field presents opportunities to further elucidate the effects that GNPs may have on biological systems.Master
The cross-tissue metabolic response of abalone (Haliotis midae) to functional hypoxia
No full textFunctional hypoxia is a stress condition caused by the abalone itself as a result of increased muscle activity, which generally necessitates the employment of anaerobic metabolism if the activity is sustained for prolonged periods. With that being said, abalone are highly reliant on anaerobic metabolism to provide partial compensation for energy production during oxygen-deprived episodes. However, current knowledge on the holistic metabolic response for energy metabolism during functional hypoxia, and the contribution of different metabolic pathways and various abalone tissues towards the overall accumulation of anaerobic end-products in abalone are scarce. Metabolomics analysis of adductor muscle, foot muscle, left gill, right gill, haemolymph and epipodial tissue samples indicated that South African abalone (Haliotis midae) subjected to functional hypoxia utilises predominantly anaerobic metabolism, and depends on all of the main metabolite classes (proteins, carbohydrates and lipids) for energy supply. Functional hypoxia caused increased levels of anaerobic end-products: lactate, alanopine, tauropine, succinate and alanine. Also, elevation in arginine levels was detected, confirming that abalone use phosphoarginine to generate energy during functional hypoxia. Different tissues showed varied metabolic responses to hypoxia, with functional hypoxia showing excessive changes in the adductor muscle and gills. From this metabolomics investigation, it becomes evident that abalone are metabolically able to produce sufficient amounts of energy when functional hypoxia is experienced. Also, tissue interplay enables the adjustment of H. midae energy requirements as their metabolism shifts from aerobic to anaerobic respiration during functional hypoxia. This article has an associated First Person interview with the first author of the paper
Obesity and metabolomics: metallothioneins protect against high-fat diet-induced consequences in metallothionein knockout mice
No full textObesity continues to rise as an alarming global epidemic. System level mechanisms, diagnostics, and therapeutics are sorely needed so as to identify at risk individuals and design appropriate population scale interventions. The present study evaluated the protective role of metallothioneins (MTs) against obesity and high-fat diet-induced effects such as insulin resistance in both male and female MT-1+2 knockout and MT-3 knockout mice. As the metabolome is closest to the functional phenotype, changes in metabolite levels were also evaluated, and the direct or indirect involvement of MTs in metabolism examined. MT-1+2−, MT-3 knockout, and wild-type mice were given a high-fat diet for 2 months. Variation in body weight gain, tissue weight, and response to oral glucose tolerance test and insulin tolerance test were determined and compared to mice that received the control diet. Effect of the high-fat diet on the knockout mice were investigated on the metabolome level in specific tissues using metabolomics. Both knockout mice strains were more susceptible to high-fat diet-induced effects, such as weight gain and moderate insulin resistance, with the MT-3 knockout mice most susceptible. Brain tissue of the knockout mice showed most metabolic variation and pointed to possible impairment of mitochondrial function. The protective effect of MTs against high-fat diet and obesity-induced effects such as insulin resistance was evident from our observations. The putative role MTs play in mitochondrial function is possibly the main contributor to the lack of these effects in wild-type mice. Considering the expression profiles of the MT isoforms and similarity in brain metabolic variation in the knockout strains, it appears that they promote mitochondrial function in the hypothalamus, thereby limiting weight gain and insulin resistance. Furthermore, metabolomics research in preclinical models of obesity and in the clinic is warranted in the near futur
The effect of temperature on the respiration and metabolism of the African burrowing scorpion (Opistophthalmus latimanus)
No full textIt is well known that scorpions are highly adapted to thermal temperatures. However, little is known of the metabolic
and respiration adaptations caused by temperature fluctuations in these animals. Therefore we used the
African burrowing scorpion Opistophthalmus latimanus to measure the effect of temperature on its metabolism
and respiration.
Radioactive D-glucose was injected into the ventral sinus of the circulatory system and metabolites of D-glucose
were determined after six hour incubation at four temperatures (7, 17, 25 and 37 °C). The oxygen consumption
rate (ṀO2) and carbon dioxide production rate (ṀCO2) were measured simultaneously at 17, 25 and 37 °C. The
metabolomics investigation included LC-MS, GC–MS and NMR analytical platforms.
The average radioactivity recovered after the carbon-14 D-glucose injection, glycogen precipitation and column
fractionation at the four temperatures was between 92.4% and 95.0%. Strong acids, CO2 and neutral compounds
all increased with temperature, while glycogen and neutral sugars decreased as the temperature increased. Weak
acids initially increased with temperature, then decreased again as the temperature was increased to 37 °C. Respiration
also gradually increased as the temperature was increased. Metabolomics identified 23 metabolites that
were significantly influenced by temperature. Pathway analysis of these metabolites indicated numerous metabolic
pathways that were affected by temperature, clearly demonstrating that the scorpion uses proteins, lipids
and carbohydrates at higher temperatures to generate energy. However, protein catabolism seems to be the
main source of energy at higher temperatures in these animals, although this needs to be confirmed in a more
targeted metabolomics stud
Use of metabolomics to elucidate the metabolic perturbation associated with hypertension in a black South African male cohort: the SABPA study
No full textThere is concern about the increasing burden of essential hypertension in urban–dwelling black South Africans, especially
males. Several studies have investigated urbanization and hypertension in South Africans, but in–depth metabolomics studies
on these urbanized hypertensives are still lacking. We aimed to investigate hypertension via two metabolomics methods in
order to explore underlying biological mechanisms, demonstrating the effectiveness of these methods in cardiovascular
research. A comprehensive characterization of a group (n = 25) of black male South Africans was performed using urinary
gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry metabolic profiling in conjunction
with 24–hour ambulatory blood pressure readings and anthropometric, clinical, and biochemical markers. Average
24–hour blood pressure readings served as the grouping variable, and test subjects were divided into quintiles. Statistical analyses
were performed on Quintile 1 (normotensive subjects) and Quintile 5 (extreme hypertensive subjects). After feature
selection was performed, several metabolites and cardiometabolic risk markers, including abdominal obesity and markers
of liver damage, inflammation, and oxidative stress were significantly perturbed in Quintile 5 (hypertensives) compared
with Quintile 1 (P < .05). Pathway analysis revealed perturbations in several systems involved in ethanol metabolism via
shifted global NADH/NAD ratio. Although alcohol abuse has been established as a risk factor for hypertension, this study
illustrated a metabolic perturbation associated with alcohol abuse, contributing to the development of hypertension—possibly
by altering bioenergetics through a shift in the NADH/NAD ratio. Following this finding, future intervention studies on
alcohol moderation, as well as further enhancement of metabolomics methods in cardiovascular research are highly recommended
Metabolomics of urinary organic acids in respiratory chain deficiencies in children
No full textThis study formed part of BioPAD Project BPP007.Metabolomic analysis of the urinary organic acids from 39 selected children with defined respiratory chain
deficiencies (RCDs) was performed using untargeted gas chromatography–mass spectrometry, revealing the
presence of 255 endogenous and 46 exogenous substances. Variable reduction identified 92 variables from the
endogenous substances, which could be analysed by univariate and multivariate statistical methods. Using
these methods, no characteristic organic acid biomarker profile could be defined of practical value for diagnostic
purposes for complex I (CI), complex III (CIII) and multiple complex (CM) deficiencies. The statistical procedures
used did, however, disclose 24 metabolites that were practical highly (d > 0.75) and statistically (p < 0.05)
significant for the combined and clinically closely related group of RCDs. Several of these metabolites occur in
single enzyme inherited metabolic diseases, but most were not previously reported to be linked to the metabolic
perturbations that are due to RCDs. Ultimately, we constructed a global metabolic profile of carbohydrate, amino
acid and fatty acid catabolism, illuminating the diverse and complex biochemical consequences of these
disorders. This metabolomics investigation disclosed a metabolite profile that has the potential to define an extended and characteristic biosignature for RCDs and the development of a non-invasive screening procedure
for these disorders.The South African Department of Science and Technology and North-West University.http://link.springer.com/journal/11306hb2017Paediatrics and Child Healt
A metabolomics investigation of a nanogold drug vehicle on experimental animals
No full textMSc (Biochemistry), North-West University, Potchefstroom CampusNanotechnology has increasingly received attention the last few decades and the term refers to the categories of applied science and technology, where the combining key subject is the study of matter in scales of 1 to 100 nm and the designing of devices within that size range. Gold nanoparticles have especially drawn massive scientific attention; the reasons being that these particles exhibit high chemical stability and unique optical properties. Furthermore, gold nanoparticles can be easily synthesised and modified, while providing great potential for a drug delivery vehicle. There is however a gap in current research with regards to the safety and effect of these particles, especially in the field of metabolomics. This study thus aimed to provide a more comprehensive view of the effect of gold nanoparticles on the metabolome, by implementing an animal model. Two groups of Sprague-Dawley rats were monitored: one control group and one treatment group. The control group received a 0.9% saline solution and the treatment group received a solution of gold nanoparticles dispersed in citrate (90μg/500μl). Urine was collected at different time points over the course of 48 hours. The study utilised three different, but effective, platforms popular within the field of metabolomics, namely 1-dimensional Nuclear Magnetic Resonance (1H-NMR) spectroscopy, Liquid Chromatography Mass Spectrometry and Gas-chromatography Time-Of-Flight Mass Spectrometry (GC-TOF/MS). Urine samples were analysed via these platforms using both untargeted and targeted metabolomics approaches, investigating an array of metabolites (including amino acids, acylcarnitines and organic acids). The data was subjected to bio-statistical analysis to identify the relevant changes in metabolite levels and produce a full list of significant compounds affected by the intervention of gold nanoparticles. The significant metabolites brought forth evidence of possible perturbation within the pathways of energy metabolism as well as carbon- and amino acid metabolism. The results were found to produce a similar profile to that of many heavy metals, in the sense that binding with sulphur-containing molecules occurred readily and consequently inhibiting the function of several proteins and enzymes. The most prominent findings were linked to the enzyme dehydrogenase family and the thiol-rich compounds of the amino acid pathways, which are often associated with a phenotype similar to heavy metal poisoning. Therefore, it is reasoned as is in the case of other heavy metals, that gold (even in nanoform) possesses a high affinity for sulphur-containing compounds and will promptly replace these bonds, by displacing the original ion.National Research Foundation (NRF)Master
The Special Aspects of Venture Capital’s Value Creating Mechanisms in Hungary
No full textThe current article focuses on the special aspects of venture capital’s value creation
methods, summarizing the author’s researches in this field. This article puts special
emphasis on the scrutiny of the Hungarian market as the value creation practices
on the domestic market have not been revealed thoroughly in the literature yet.
The article attempts to examine the performance of venture capital, especially the
JEREMIE funds, according to the limited available secondary data of the companies
involved, which helps to assess the role of the government in bridging the financial
gap and solving the problems in the venture capital market in Hungary. In this field
reliable statistical data is not available, but there is an ongoing primer research led
by the author, producing new information soon. The article presents the special
investment and value creating methods of venture capitalists. In the first part of the
article the theoretical background is presented, and in the second part of the article
the author’s research results are demonstrated following the same order.Artykuł stanowi podsumowanie obszernych badań autorki i skupia się na metodach
kreowania wartości przez fundusze venture capital. Rozpoczyna się przeglądem literatury,
w którym opisano podstawy teoretyczne kreowania wartości. W drugiej czę-
ści artykułu przedstawiono badania empiryczne na rynku węgierskim, dla którego
praktyki inwestorów w zakresie kreowania wartości nie zostały dostatecznie opisane
w literaturze przedmiotu. W związku z tym, że w krajach europejskich państwo jest
obecnie jednym z największych inwestorów w fundusze VC wspierającym projekty
we wczesnej fazie rozwoju, w artykule zwrócono szczególną uwagę na rolę państwa
na rynku VC. W tym kontekście wybór rynku węgierskiego jest uzasadniony, z tego
względu, że rząd tego kraju dysponował największą pulą środków w Europie Środkowo-Wschodniej
pochodzącą z Inicjatywy JEREMIE, którą ulokował w funduszach
hybrydowych podwyższonego ryzyka. Wnioski z zaprezentowanych badań są nastę-
pujące: podczas gdy wsparte przez rząd fundusze VC wywierają efekt stymulujący
na rozwój rynku VC, to wycofanie się państwa w długim okresie z aktywnego zaangażowania
i przyjęcie pasywnej postawy może być bardziej skuteczne w pobudzaniu
efektywności rynku V
Sub-Cellular Metabolomics Contributes Mitochondria-Specific Metabolic Insights to a Mouse Model of Leigh Syndrome
No full textDirect injury of mitochondrial respiratory chain (RC) complex I by Ndufs4 subunit mutations results in complex I deficiency (CID) and a progressive encephalomyopathy, known as Leigh syndrome. While mitochondrial, cytosolic and multi-organelle pathways are known to be involved in the neuromuscular LS pathogenesis, compartment-specific metabolomics has, to date, not been applied to murine models of CID. We thus hypothesized that sub-cellular metabolomics would be able to contribute organelle-specific insights to known Ndufs4 metabolic perturbations. To that end, whole brains and skeletal muscle from late-stage Ndufs4 mice and age/sex-matched controls were harvested for mitochondrial and cytosolic isolation. Untargeted 1H-NMR and semi-targeted LC-MS/MS metabolomics was applied to the resulting cell fractions, whereafter important variables (VIPs) were selected by univariate statistics. A predominant increase in multiple targeted amino acids was observed in whole-brain samples, with a more prominent effect at the mitochondrial level. Similar pathways were implicated in the muscle tissue, showing a greater depletion of core metabolites with a compartment-specific distribution, however. The altered metabolites expectedly implicate altered redox homeostasis, alternate RC fueling, one-carbon metabolism, urea cycling and dysregulated proteostasis to different degrees in the analyzed tissues. A first application of EDTA-chelated magnesium and calcium measurement by NMR also revealed tissue- and compartment-specific alterations, implicating stress response-related calcium redistribution between neural cell compartments, as well as whole-cell muscle magnesium depletion. Altogether, these results confirm the ability of compartment-specific metabolomics to capture known alterations related to Ndufs4 KO and CID while proving its worth in elucidating metabolic compartmentalization in said pathways that went undetected in the diluted whole-cell samples previously studied
Identification of nine new susceptibility loci for testicular cancer, including variants near DAZL and PRDM14.
No full textTesticular germ cell tumor (TGCT) is the most common cancer in young men and is notable for its high familial risks. So far, six loci associated with TGCT have been reported. From genome-wide association study (GWAS) analysis of 307,291 SNPs in 986 TGCT cases and 4,946 controls, we selected for follow-up 694 SNPs, which we genotyped in a further 1,064 TGCT cases and 10,082 controls from the UK. We identified SNPs at nine new loci (1q22, 1q24.1, 3p24.3, 4q24, 5q31.1, 8q13.3, 16q12.1, 17q22 and 21q22.3) showing association with TGCT (P < 5 × 10(-8)), which together account for an additional 4-6% of the familial risk of TGCT. The loci include genes plausibly related to TGCT development. PRDM14, at 8q13.3, is essential for early germ cell specification, and DAZL, at 3p24.3, is required for the regulation of germ cell development. Furthermore, PITX1, at 5q31.1, regulates TERT expression and is the third TGCT-associated locus implicated in telomerase regulation
