965 resultados para Biochemical and molecularcharacterization
Resumo:
Riboflavin-responsive, multiple acylcoenzyme A dehydrogenase deficiency (RR-MAD), a lipid storage myopathy, is characterized by, among others, a decrease in fatty acid (FA) ß-oxidation capacity. Muscle uncoupling protein 3 (UCP3) is up-regulated under conditions that either increase the levels of circulating free FA and/or decrease FA ß-oxidation. Using a relatively large cohort of seven RR-MAD patients, we aimed to better characterize the metabolic disturbances of this disease and to explore the possibility that it might increase UCP3 expression. A battery of biochemical and molecular tests were performed, which demonstrated decreases in FA ß-oxidation and in the activities of respiratory chain complexes I and II. These metabolic alterations were associated with increases of 3.1- and 1.7-fold in UCP3 mRNA and protein expression, respectively. All parameters were restored to control values after riboflavin treatment. We postulate that the up-regulation of UCP3 in RR-MAD is due to the accumulation of muscle FA/acylCoA. RR-MAD is an optimal model to support the hypothesis that UCP3 is involved in the outward translocation of an excess of FA from the mitochondria and to show that, in humans, the effects of FA on UCP3 expression are direct and independent of fatty acid ß-oxidation.
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In this article, we explore the role of the C-terminus (V5 domain) of PKCvar epsilon plays in the catalytic competence of the kinase using serial truncations followed by immune-complex kinase assays. Surprisingly, removal of the last seven amino acid residues at the C-terminus of PKCvar epsilon resulted in a PKCvar epsilon-Δ731 mutant with greatly reduced intrinsic catalytic activity while truncation of eight amino acid residues at the C-terminus resulted in a catalytically inactive PKCvar epsilon mutant. Computer modeling and molecular dynamics simulations showed that the last seven and/or eight amino acid residues of PKCvar epsilon were involved in interactions with residues in the catalytic core. Further truncation analyses revealed that the hydrophobic phosphorylation motif was dispensable for the physical interaction between PKCvar epsilon and 3-phosphoinositide-dependent kinase-1 (PDK-1) as the PKCvar epsilon mutant lacking both the turn and the hydrophobic motifs could still be co-immunoprecipitated with PDK-1. These results provide fresh insights into the biochemical and structural basis underlying the isozyme-specific regulation of PKC and suggest that the very C-termini of PKCs constitute a promising new target for the development of novel isozyme-specific inhibitors of PKC.
Resumo:
Acute myocardial infarction (M!) is the commonest cause of death in the developed countries, and it is on the rise in developing countries. Ramipril is a well-knownAngiotensin-converting enzyme (ACE) inhibitorwhich inhibits conversion ofinactive angiotensin I to active angiotensin II. Experimental studies have shown thatACE inhibitors administered chronicallybefore acuteMImight limitmyocardial infarct size, improve cardiac function and prevent cardiac hypertrophy [1, 2]. The Chinese herb, Salvia miltiorrhiza (SM), has been widely and successfully usedmainly for anginapectoris,MI and stroke [3]. Compared to ramipril, however, there is very limited biochemical information availableto demonstrate themechanismsofSMs
cardio-protective effects. This study thus investigates the possible
biochemical and molecularmechanisms ofsuch effects ofSMin Wistar rats in comparison with those oframipril.
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Objective: To explore the hypothesis that sustained weight loss in severely obese patients may have benefits that are independent of their attained BMI. Research Methods and Procedures: We conducted a comparison of two weight-stable groups with BMI in the 30 to 35 kg/m2 range. Subjects (n = 79) were selected obese patients 3 years after laparoscopic adjustable gastric band surgery, and controls (n = 79) were obese patients seeking weight loss therapy. Subjects were selected in a de-identified manner from our database to best match the control group. A range of clinical, biochemical, and questionnaire measures were obtained to assess obesity-related health status Results: Subjects maintained a mean weight loss of 32.8 plusminus 18 kg after surgery. The weight loss subjects had significantly lower fasting plasma glucose, insulin, and triglyceride concentrations, along with higher high-density lipoprotein-cholesterol levels and better indirect measures of insulin sensitivity when compared with controls (p < 0.05 for all). In addition, aminotransferase levels, neutrophil counts, and globulin levels were also significantly lower in weight loss subjects. All differences in laboratory variables remained significant after controlling for BMI. The subjects also reported better health-related quality of life, fewer symptoms of depression, and greater satisfaction with their appearance than controls. Discussion: These findings suggest that the post-weight loss state conveys benefits that are greater than predicted by the attained BMI. These findings may have important implications regarding the expectations of weight loss therapy, and mechanisms for this effect should be carefully sought.
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Objective To illustrate the effect of common mistakes when using 24-hour national dietary survey data to estimate the prevalence of inadequate nutrient intakes.
Design Raw data on nutrient intake from the Australian 1995 National Nutrition Survey were adjusted for within-person variance using standard techniques and corrected for underreporting using the criteria of Goldberg et al. The distributions for six nutrients were compared with current dietary reference values from the UK, USA and Australia.
Setting A national sample of the Australian population with a 61.4% response rate.
Results Adjusting for within-person variance reduced the range of nutrient intakes to 66–80% of the raw data range and the proportion with intakes below the estimated average requirement (EAR) by up to 20%. Excluding underreporters further reduced the proportion below the EAR by up to 10%. Using the dietary reference values from different countries also resulted in some markedly different estimates. For example, the prevalence of low folate intakes ranged from <1 to 92% for adult women depending on the reference used. Except for vitamin A and protein, the prevalence of low intakes was invariably higher for women than for men.
Conclusions Estimates of the prevalence of low nutrient intakes based on raw 24-hour survey data are invariably misleading. However, even after adjustment for within-person variance and underreporting, estimates of the prevalence of low nutrient intakes may still be misleading unless interpreted in the light of the reference criteria used and supported by relevant biochemical and physiological measures of nutritional status.
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The flood of new genomic sequence information together with technological innovations in protein structure determination have led to worldwide structural genomics (SG) initiatives. The goals of SG initiatives are to accelerate the process of protein structure determination, to fill in protein fold space and to provide information about the function of uncharacterized proteins. In the long-term, these outcomes are likely to impact on medical biotechnology and drug discovery, leading to a better understanding of disease as well as the development of new therapeutics. Here we describe the high throughput pipeline established at the University of Queensland in Australia. In this focused pipeline, the targets for structure determination are proteins that are expressed in mouse macrophage cells and that are inferred to have a role in innate immunity. The aim is to characterize the molecular structure and the biochemical and cellular function of these targets by using a parallel processing pipeline. The pipeline is designed to work with tens to hundreds of target gene products and comprises target selection, cloning, expression, purification, crystallization and structure determination. The structures from this pipeline will provide insights into the function of previously uncharacterized macrophage proteins and could lead to the validation of new drug targets for chronic obstructive pulmonary disease and arthritis.
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The biochemical and molecular processes that maintain the stem cell pool, and govern the proliferation and differentiation of haemopoietic stem/progenitor cells (HSPCs) have been widely investigated but are incompletely understood. The purpose of this study was to identify and characterise novel genes that may play a part in regulating the mechanisms that control the proliferation, differentiation and self-renewal of human HSPCs. Reverse transcription differential display polymerase chain reaction (dd-PCR) was used to identify differences in gene expression between a HSPC population defined by expression of the CD34 phenotype, and the more mature CD34 depleted populations. A total of 6 differentially expressed complementary deoxyribonucleic acid (cDNA) sequences were identified. Four of these transcripts were homologous to well characterised genes, while two (band 1 and band 20) were homologous to unknown and uncharacterised partial gene sequences on the GenBank database and were thus chosen for further investigation. The partial cDNA sequences for band 1 and band 20 were designated ORP-3 and MERP-1 (respectively) due to homologies with other well-characterised gene families. Differential expression of the ORP-3 and MERP-1 genes was confirmed using Taqman™ real-time polymerase chain reaction (PCR) with 3 - 4-fold and 4-10 -fold higher levels in the CD34+ fractions of haemopoietic cells compared to CD34- populations respectively. Additionally, expression of both these genes was down regulated with proliferation and differentiation of CD34+ cells further confirming higher expression in a less differentiated subset of haemopoietic cells. The full coding sequences of ORP-3 and MERP-1 were elucidated using bioinformatics, rapid amplification of cDNA ends (RACE) and PCR amplification. The MERP-1 cDNA is 2600 nucleotides (nt) long, and localizes by bioinformatics to chromosome 7.. It consists of three exons and 2 introns spanning an entire length of 31.4 kilobases (kb). The MERP-1 open reading frame (ORF) codes for a putative 344 amino acid (aa) type II transmembrane protein with an extracellular C-terminal ependymin like-domain and an intracellular N-terminal sequence with significant homology to the cytoplasmic domains of members of the protocadherin family of transmembrane glycoproteins. Ependymins and protocadherins are well-characterised calcium-dependant cell adhesion glycoproteins. Although the function of MERP-1 remains to be elucidated, it is possible that MERP-1 like its homologues plays a role in calcium dependent cell adhesion. Differential expression of the MERP-1 gene in haemopoietic cells suggests a role in haemopoietic stem cell proliferation and differentiation, however, its broad tissue distribution implies that it may also play a role in many cell types. Characterization of the MERP-1 protein is required to elucidate these possible roles. The ORP-3 cDNA is 6631nt long, and localizes by bioinformatics to chromosome 7pl5-p21. It consists of 23 exons and 22 introns spanning an entire length of 183.5kb. The ORP-3 ORF codes for a putative 887aa protein which displays the consensus sequence for a highly conserved oxysterol-binding domain. Other well-characterised proteins expressing these domains have been demonstrated to bind oxysterols (OS) in a dose dependant fashion. OS are hydroxylated derivatives of cholesterol Their biological activities include inhibition of cholesterol biosynthesis and cell proliferation in a variety of cell types, including haemopoietic cells. Differential expression of the ORP-3 gene in haemopoietic cells suggests a possible role in the transduction of OS effects on haemopoietic cells, however, its broad tissue distribution implies that it may also play a role in many cell types. Further investigation of ORP-3 gene expression demonstrates a significant correlation with CD34+ sample purity, and 2-fold higher expression in a population of haemopoietic cells defined by the CD34+38- phenotype compared to more mature CD34+38+ cells. This finding, taken together with the previous observation of down-regulation of ORP-3 expression with proliferation and differentiation of CD34+ cells, indicates that ORP-3 expression may be higher in a less differentiated subset of cells with a higher proliferative capacity. This hypothesis is supported by the observation that expression of the ORP-3 gene is approximately 2-fold lower in differentiated HL60 promyelocytic cells compared to control, undifferentiated cells. ORP-3 expression in HL60 cells during normal culture conditions was also found to vary with expression positively correlated with cell number. This indicates a possible cell cycle effect on ORP-3 gene expression with levels highest when cell density, and therefore the percentage of cells in G(0)/G(1) phase of the cell cycle is highest. This observation also correlates with the observation of higher ORP-3 expression in CD34+38-cells, and in CD34+ and HL60 cells undergoing OS induced and camptothecin induced apoptosis that is preceded by cell cycle arrest at G(0)/G(1). Expression of the ORP-3 gene in CD34+ HSPCs from UCB was significantly decreased to approximately half the levels observed in control cells after 24 hours incubation in transforming growth factor beta-1 (TGFâl). As ≥90% of these cells are stimulated into cell cycle entry by TGFâl, this observation further supports the hypothesis that ORP-3 expression is highest when cells reside in the G(0)/G(1) phase of the cell cycle. Data obtained from investigation of ORP-3 gene expression in synchronised HL60 cells however does not support nor disprove this hypothesis. Culture of CD34+ enriched HSPCs and HL60 cells with 25-OHC significantly increased ORP-3 gene expression to approximately 1.5 times control levels. However, as 25-OHC treatment also increased the percentage of apoptotic cells in these experiments, it is not valid to make any conclusions regarding the regulation of ORP-3 gene expression by OS. Indeed, the observation that camptothecin induced apoptosis also increased ORP-3 gene expression in HL60 cells raises the possibility that up-regulation of ORP-3 gene expression is also associated with apoptosis, Taken together, expression of the ORP-3 gene appears to be regulated by differentiation and apoptosis of haemopoietic progenitors, and may also be positively associated with proliferative and G(0)/G(1) cell cycle status indicating a possible role in all of these processes. Given the important regulatory role of apoptosis in haemopoiesis and differential expression of the ORP-3 gene in haemopoietic progenitors, final investigations were conducted to examine the effects OS on human HSPCs. Granulocyte/macrophage colony forming units (CFU-GM) generated from human bone marrow (ABM) and umbilical cord blood (UCB) were grown in the presence of varying concentrations of three different OS - 7keto-cholesterol (7K-C), 7beta-hydroxycholesterol (7p-OHC) and 25-hydroxycholesterol (25-OHC). Similarly, the effect of OS on HL60 and CD34+ cells was investigated using annexin-V staining and flow cytometry to measure apoptosis. Reduction of nitroblue tetrazolium (NBT) was used to assess differentiative status of HL60 cells. CFU-GM from ABM and HL60 growth was inhibited by all three OS tested, with 25-OHC being the most potent. 25-OHC inhibited ≥50% of bone marrow CFU-GM and ≥95% of HL60 cell growth at a level of 1 ug/ml. Compared to UCB, CFU-GM derived from ABM were more sensitive to the effects of all OS tested. Only 25-OHC and 7(5-OHC significantly inhibited growth of UCB derived CFU-GM. OS treatment increased the number of annexin-V CD34+ cells and NBT positive HL60 cells indicating that OS inhibition of CFU-GM and HL60 cell growth can be attributed to induction of apoptosis and differentiation. From these studies, it can be concluded that dd-PCR is an excellent tool for the discovery of novel genes expressed in human HSPCs. Characterisation of the proteins encoded by the novel genes ORP-3 and MERP-1 may reveal a regulatory role for these genes in haemopoiesis. Finally, investigations into the effects of OS on haemopoietic progenitor cells has revealed that OS are a new class of inhibitors of HSPC proliferation of potential relevance in vivo and in vitro.
Resumo:
The plant hormone, abscisic acid (ABA), has previously been shown to have an impact on the resistance or susceptibility of plants to pathogens. In this thesis, it was shown that ABA had a regulatory effect on an extensive array of plant defence responses in three different plant and pathogen interaction combinations as well as following the application of an abiotic elicitor. In unique studies using ABA deficient mutants of Arabidopsis, exogenous ABA addition or ABA biosynthesis inhibitor application and simulated drought stress, ABA was shown to have a profound effect on the outcome of interactions between plants and pathogens of differing lifestyles and from different kingdoms. The systems used included a model plant and an important agricultural species: Arabidopsis thaliana (Arabidopsis) and Peronospora parasitica (a biotrophic Oomycete pathogen), Arabidopsis and Pseudomonas syringae pathovar tomato (a biotrophic bacterial pathogen) and an unrelated plant species, soybean (Glycine max) and Phytophthora sojae (a hemibiotrophic Oomycete pathogen), Generally, a higher than basal endogenous ABA concentration within plant tissues at the time of avirulent pathogen inoculation, caused an interaction shift towards what phenotypically resembled susceptibility. Conversely, a lower than basal endogenous ABA concentration in plants inoculated with a virulent pathogen caused a shift towards resistance. An extensive suppressive effect of ABA on defence responses was revealed by a range of techniques that included histochemical, biochemical and molecular approaches. A universal effect of ABA on suppression or induction of the phenylpropanoid pathway via regulation of the key entry point gene, phenylalanine ammonia-lyase (PAL), when stimulated by biotic or abiotic elicitors was shown. ABA also influenced a wide variety of other defence-related components such as: the development of a hypersensitive response (HR), the accumulation of the reactive oxyden species, hydrogen peroxide and the cell wall strengthening compounds lignin and callose, accumulation of SA and the phytoalexin, glyceollin and the transcription of the SA-dependent pathogenesis- related gene (PR-1). The near genome-wide microarray gene expression analysis of an ABA induced susceptible interaction also revealed an yet unprecedented insight into the great diversity of defence responses that were influenced by ABA that included: disease resistance like proteins, antimicrobial proteins as well as phenylpropanoid and tryptophan pathway enzymes. Subtle differences were found in the number and type of defence responses that were regulated by ABA in each type of plant and pathogen interaction that was studied. This thesis has clearly identified in plant/pathogen interactions previously unknown and important roles for ABA in the regulation of many defence responses.
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Background: Rural Australians face a higher mental health and lifestyle disease burden (obesity, diabetes and
cardiovascular disease) than their urban counterparts. Our ongoing research reveals that the Australian farming
community has even poorer physical and mental health outcomes than rural averages. In particular, farm men and
women have high rates of overweightness, obesity, abdominal adiposity, high blood pressure and psychological
distress when compared against Australian averages. Within our farming cohort we observed a significant
association between psychological distress and obesity, abdominal adiposity and body fat percentage in the
farming population.
Presentation of hypothesis: This paper presents a hypothesis based on preliminary data obtained from an
ongoing study that could potentially explain the complex correlation between obesity, psychological distress and
physical activity among a farming population. We posit that spasmodic physical activity, changing farm practices
and climate variability induce prolonged stress in farmers. This increases systemic cortisol that, in turn, promotes
abdominal adiposity and weight gain.
Testing the hypothesis: The hypothesis will be tested by anthropometric, biochemical and psychological analysis
matched against systemic cortisol levels and the physical activity of the subjects.
Implications of the hypothesis tested: Previous studies indicate that farming populations have elevated rates of
psychological distress and high rates of suicide. Australian farmers have recently experienced challenging climatic
conditions including prolonged drought, floods and cyclones. Through our interactions and through the media it is
not uncommon for farmers to describe the effect of this long-term stress with feelings of ‘defeat’. By gaining a
greater understanding of the role cortisol and physical activity have on mental and physical health we may
positively impact the current rates of psychological distress in farmers.
Resumo:
Smooth polymerized surfaces, suitable for biochemical and biomedical applications, were deposited using a modified plasma enhanced chemical vapour deposition method with acetylene as a reaction precursor. Horseradish peroxidase (HRP) activity assays showed that the protein immobilized on the plasma polymerized surfaces maintained its biological function for a much longer period of time compared to that on uncoated surfaces. The kinetics of HRP attachment to the plasma polymerized surfaces were analyzed using quartz crystal microbalance with dissipation analysis. Spectroscopic ellipsometry and attenuated total reflection Fourier transform infrared spectroscopy were used to determine the thickness and the quantity of the attached protein. The results showed that the plasma polymerized surfaces provided a high density of attachment sites to covalently immobilize a dense monolayer of proteins.
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Objectives
Using 2 sequential studies in HOPE (Heart Outcomes Prevention Evaluation) study–type patients, the aims of this study were: 1) to test the hypothesis that ramipril improves platelet nitric oxide (NO) responsiveness: and 2) to explore biochemical and physiological effects of ramipril in a cohort selected on the basis of platelet NO resistance.
Background
Ramipril prevents cardiovascular events, but the bases for these effects remain uncertain. NO resistance at both the platelet and vascular levels is present in a substantial proportion of patients with diabetes or ischemic heart disease and is an independent risk factor for cardiovascular events.
Methods
Study 1 was a double-blind, randomized comparison of ramipril (10 mg) with placebo in a cohort of patients (n = 119) with ischemic heart disease or diabetes plus additional coronary risk factor(s), in which effects on platelet responsiveness to NO were compared. Study 2 was a subsequent short-term evaluation of the effects of ramipril in a cohort of subjects (n = 19) with impaired platelet NO responsiveness in whom additional mechanistic data were sought.
Results
In study 1, ramipril therapy increased platelet responsiveness to NO relative to the extent of aggregation (p < 0.001), but this effect occurred primarily in patients with severely impaired baseline NO responsiveness (n = 41). In study 2, ramipril also improved platelet NO responsiveness (p < 0.01), and this improvement was correlated directly with increased NO-stimulated platelet generation of cyclic guanosine monophosphate (p < 0.02) but not with changes in plasma thrombospondin-1 levels.
Conclusions
Ramipril ameliorates platelet NO resistance in HOPE study–type patients, with associated increases in soluble guanylate cyclase responsiveness to NO. This effect is likely to contribute to treatment benefit and define patients in whom ramipril therapy is particularly effective.
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Background and AimsA major impediment to establishing new treatments for non-alcoholic steatohepatitis is the lack of suitable animal models that accurately mimic the biochemical and metabolic characteristics of the disease. The aim of this study was to explore a unique polygenic animal model of metabolic disease as a model of non-alcoholic steatohepatitis by determining the effects of 2% dietary cholesterol supplementation on metabolic and liver endpoints in Psammomys obesus (Israeli sand rat).MethodsP. obesus were provided ad libitum access to either a standard rodent diet (20% kcal/fat) or a standard rodent diet supplemented with 2% cholesterol (w/w) for 4 weeks. Histological sections of liver from animals on both diets were examined for key features of non-alcoholic steatohepatitis. The expression levels of key genes involved in hepatic lipid metabolism were measured by real-time PCR.ResultsP. obesus fed a cholesterol-supplemented diet exhibited profound hepatomegaly and steatosis, and higher plasma transaminase levels. Histological analysis identified extensive steatosis, inflammation, hepatocyte injury and fibrosis. Hepatic gene expression profiling revealed decreased expression of genes involved in delivery and uptake of lipids, and fatty acid and triglyceride synthesis, and increased expression of genes involved in very low density lipoprotein cholesterol synthesis, triglyceride and cholesterol export.ConclusionsP. obesus rapidly develop non-alcoholic steatohepatitis when fed a cholesterol-supplemented diet that appears to be histologically and mechanistically similar to patients.
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Nanomaterials are rich in potential, particularly for the formation of scaffolds that mimic the landscape of the host environment of the cell. This niche arises from the spatial organization of a series of biochemical and biomechanical signals. Self-assembling peptides have emerged as an important tool in the development of functional (bio-)nanomaterials; these simple, easily synthesized subunits form structures which present the properties of these larger, more complex systems. Scaffolds based upon these nanofibrous matrices are promising materials for regenerative medicine as part of a new methodology in scaffold design where a "bottom-up" approach is used in order to simulate the native cellular milieu. Importantly, SAPs hold the potential to be bioactive through the presentation of biochemical and biomechanical signals in a context similar to the natural extracellular matrix, making them ideal targets for providing structural and chemical support in a cellular context. Here, we discuss a new methodology for the presentation of biologically relevant epitopes through their effective presentation on the surface of the nanofibers. Here, we demonstrate that these signals have a direct effect on the viability of cells within a three-dimensional matrix as compared with an unfunctionalized, yet mechanically and morphologically similar system. © 2014 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 102: 197-205, 2014.
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Background Monitoring athlete well-being is essential to guide training and to detect any progression towards negative health outcomes and associated poor performance. Objective (performance, physiological, biochemical) and subjective measures are all options for athlete monitoring. Objective We systematically reviewed objective and subjective measures of athlete well-being. Objective measures, including those taken at rest (eg, blood markers, heart rate) and during exercise (eg, oxygen consumption, heart rate response), were compared against subjective measures (eg, mood, perceived stress). All measures were also evaluated for their response to acute and chronic training load. Methods The databases Academic search complete, MEDLINE, PsycINFO, SPORTDiscus and PubMed were searched in May 2014. Fifty-six original studies reported concurrent subjective and objective measures of athlete well-being. The quality and strength of findings of each study were evaluated to determine overall levels of evidence. Results Subjective and objective measures of athlete well-being generally did not correlate. Subjective measures reflected acute and chronic training loads with superior sensitivity and consistency than objective measures. Subjective well-being was typically impaired with an acute increase in training load, and also with chronic training, while an acute decrease in training load improved subjective well-being. Summary This review provides further support for practitioners to use subjective measures to monitor changes in athlete well-being in response to training. Subjective measures may stand alone, or be incorporated into a mixed methods approach to athlete monitoring, as is current practice in many sport settings.