30 resultados para Biochemical and molecularcharacterization

em Deakin Research Online - Australia


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Storage of adzuki beans and other pulse grains causes biochemical and physical changes that affect the hydration properties of the beans. This affects the quality of products made from the beans such as the Japanese bean paste “ann.” Storage, particularly under unfavourable conditions, leads to the “hard shell” phenomenon, where beans fail to imbibe water when soaked and remain hard, and the “hard-to-cook” phenomenon where the seeds hydrate normally, but the cotyledon fails to hydrate and soften during cooking. The hard shell phenomenon is attributable to impermeability of the seed coat to water, which is due to biochemical changes in the seed coat, such as the formation of protein-tannin complexes, and biophysical changes such as reduction in size or closure of the straphiole aperture in the hilum area—the main area for water entry into the adzuki bean. The hard-to-cook phenomenon is due to changes in the cotyledon tissue, which include formation of insoluble pectinates, lignification of the cell wall and middle lamella, interaction of condensed tannins with proteins and starch, and changes to the structure and functionality of the cellular proteins and starch.

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In the absence of clear targets for primary prevention of many psychiatric illnesses, secondary prevention becomes the most feasible therapeutic target, and is best encompassed by the concept of early intervention. This construct encompasses the goals of minimising diagnostic delay and the prompt initiation of clinically appropriate therapy. This paper develops the rationale for early intervention in bipolar disorder. Three interrelated themes are discussed; the clinical data supporting the value of prompt diagnosis and treatment in bipolar disorder, the putative biochemical mechanisms underlying the pathophysiological processes, and the parallel concept of neuroprotection, and the developing neuroimaging data that supports early intervention. Early initiation of appropriate therapy may potentially facilitate improved clinical outcomes, and further might allow the secondary prevention of the sequelae of untreated illness, which include the deleterious impact on family relationships, psychosexual and vocational development, identity and self-concept and self-stigma.

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This is an update of a previous CARI Guideline on management of anaemia in CKD patients.

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Background & Aims
Nutrients putatively implicated in pressure ulcer healing were evaluated in a clinical setting.

Methods
Sixteen inpatients with a stage 2, 3 or 4 pressure ulcer randomised to receive daily a standard hospital diet; a standard diet plus two high-protein/energy supplements; or a standard diet plus two high-protein/energy supplements containing additional arginine (9 g), vitamin C (500 mg) and zinc (30 mg). Nutritional status measurements (dietary, anthropometric and biochemical) and pressure ulcer size and severity (by PUSH tool; Pressure Ulcer Scale for Healing; 0=completely healed, 17=greatest severity) were measured weekly for 3 weeks.

Results
Patients’ age and BMI ranges were 37–92 years and 16.4–28.1 kg/m2, respectively. Baseline PUSH scores were similar between groups (8.7±0.5). Only patients receiving additional arginine, vitamin C and zinc demonstrated a clinically significant improvement in pressure ulcer healing (9.4±1.2 vs. 2.6±0.6; baseline and week 3, respectively; P<0.01). All patient groups presented with low serum albumin and zinc and elevated C-reactive protein. There were no significant changes in biochemical markers, oral dietary intake or weight in any group.

Conclusions
In this small set of patients, supplementary arginine, vitamin C and zinc significantly improved the rate of pressure ulcer healing. The results need to be confirmed in a larger study.

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The segment C-terminal to the hydrophobic motif at the V5 domain of protein kinase C (PKC) is the least conserved both in length and in amino acid identity among all PKC isozymes. By generating serial truncation mutants followed by biochemical and functional analyses, we show here that the very C terminus of PKCα is critical in conferring the full catalytic competence to the kinase and for transducing signals in cells. Deletion of one C-terminal amino acid residue caused the loss of ~60% of the catalytic activity of the mutant PKCα, whereas deletion of 10 C-terminal amino acid residues abrogated the catalytic activity of PKCα in immune complex kinase assays. The PKCα C-terminal truncation mutants were found to lose their ability to activate mitogen-activated protein kinase, to rescue apoptosis induced by the inhibition of endogenous PKC in COS cells, and to augment melatonin-stimulated neurite outgrowth. Furthermore, molecular dynamics simulations revealed that the deletion of 1 or 10 C-terminal residues results in the deformation of the V5 domain and the ATP-binding pocket, respectively. Finally, PKCα immunoprecipitated using an antibody against its C terminus had only marginal catalytic activity compared with that of the PKCα immunoprecipitated by an antibody against its N terminus. Therefore, the very C-terminal tail of PKCα is a novel determinant of the catalytic activity of PKC and a promising target for selective modulation of PKCα function. Molecules that bind preferentially to the very C terminus of distinct PKC isozymes and suppress their catalytic activity may constitute a new class of selective inhibitors of PKC.

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Copper is essential for human health and copper imbalance is a key factor in the aetiology and pathology of several neurodegenerative diseases. The copper-transporting P-type ATPases, ATP7A and ATP7B are key molecules required for the regulation and maintenance of mammalian copper homeostasis. Their absence or malfunction leads to the genetically inherited disorders, Menkes and Wilson diseases, respectively. These proteins have a dual role in cells, namely to provide copper to essential cuproenzymes and to mediate the excretion of excess intracellular copper. A unique feature of ATP7A and ATP7B that is integral to these functions is their ability to sense and respond to intracellular copper levels, the latter manifested through their copper-regulated trafficking from the transGolgi network to the appropriate cellular membrane domain (basolateral or apical, respectively) to eliminate excess copper from the cell. Research over the last decade has yielded significant insight into the enzymatic properties and cell biology of the copper-ATPases. With recent advances in elucidating their localization and trafficking in human and animal tissues in response to physiological stimuli, we are progressing rapidly towards an integrated understanding of their physiological significance at the level of the whole animal. This knowledge in turn is helping to clarify the biochemical and cellular basis not only for the phenotypes conferred by individual Menkes and Wilson disease patient mutations, but also for the clinical variability of phenotypes associated with each of these diseases. Importantly, this information is also providing a rational basis for the applicability and appropriateness of certain diagnostic markers and therapeutic regimes. This overview will provide an update on the current state of our understanding of the localization and trafficking properties of the copper-ATPases in cells and tissues, the molecular signals and posttranslational interactions that govern their trafficking activities, and the cellular basis for the clinical phenotypes associated with disease-causing mutations.

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The MNK (Menkes disease protein; ATP7A) is a major copper- transporting P-type ATPase involved in the delivery of copper to cuproenzymes in the secretory pathway and the efflux of excess copper from extrahepatic tissues. Mutations in the MNK (ATP7A) gene result in Menkes disease, a fatal neurodegenerative copper deficiency disorder. Currently, detailed biochemical and biophysical analyses of MNK to better understand its mechanisms of copper transport are not possible due to the lack of purified MNK in an active form. To address this issue, we expressed human MNK with an N-terminal Glu-Glu tag in Sf9 [Spodoptera frugiperda (fall armyworm) 9] insect cells and purified it by antibody affinity chromatography followed by size-exclusion chromatography in the presence of the non-ionic detergent DDM (n-dodecyl b-D-maltopyranoside). Formation of the classical vanadate-sensitive phosphoenzyme by purified MNK was activated by Cu(I) [EC50=0.7 µM; h (Hill coefficient) was 4.6]. Furthermore, we report the first measurement of Cu(I)-dependent ATPase activity of MNK (K0.5=0.6 µM; h=5.0). The purified MNK demonstrated active ATP-dependent vectorial 64Cu transport when reconstituted into soya-bean asolectin liposomes. Together, these data demonstrated that Cu(I) interacts with MNK in a co-operative manner and with high affinity in the sub-micromolar range. The present study provides the first biochemical characterization of a purified full-length mammalian copper-transporting P-type ATPase associated with a human disease.

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Phytophthora cinnamomi is a soil borne plant pathogen that causes devastating disease in many Australian ecosystems and threatens the survival of native flora. Compared with the number of plant species that are susceptible to P. cinnamomi, only a few species are known to be resistant and control of this pathogen by chemicals is difficult and undesirable in natural systems. The major aim of our research is therefore to characterise natural resistance and determine which signalling pathways and defence responses are involved. Our examination of resistance is being approached at several levels, one of which is through the use of the model plant, Arabidopsis. Previously, Arabidopsis had been shown to display ecotypic variation in responses to P. cinnamomi and we are exploring this further in conjunction with the analysis of a bank of Arabidopsis defence pathway mutants for their responses to the pathogen. These experiments will provide a fundamental basis for further analysis of the defence responses of native plants. Native species (susceptible and resistant) are being assessed for their responses to P. cinnamomi at morphological, biochemical and molecular levels. This research also involves field-based studies of plants under challenge at various sites throughout Victoria, Australia. The focus of this field-based research is to assess the responses of individual species to P. cinnamomi in the natural environment with the goal of identifying individuals within susceptible species that display 'resistance'. Understanding how plants are able to resist this pathogen will enable strategies to be developed to enhance species survival and to restore structure and biodiversity to the ecosystems under threat.

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This thesis is concerned with the effect of alcohol consumption on the pathogenesis of bleeding from the upper gastrointestinal tract via nutritional pathways. Altered nutritional status is a frequently recognised clinical accompaniement of heavy alcohol consumption in hospitalized patients. Similarly, upper gastrointestinal bleeding is frequently accompanied by the presence of heavy alcohol consumption. Nevertheless, the clinical quantification of alcohol intake is often descriptive, so that a link between alcohol use and upper gastrointestinal haemorrhage via nutritional mechanisms has been only generally defined. In the literature review, the methods of defining alcohol use and abuse, using interview, biochemical and haematological techniques are noted. The relationship between alcohol abuse and nutrient imbalances is reviewed, especially in relation to possible effects on the gastrointestinal tract, appetite and eating habits. A further section reviews the relationship between alcohol use and anatomical lesions of the upper gastrointestinal tract likely to lead to bleeding. Following the chapter in which the methods used in this thesis are described. Chapter 4 seeks to describe the study population and its subgroups in this thesis in relation to interview, biochemical and haematological methods. Alcohol use is defined in relation to (1) a clinical classification of heavy or light drinking, based on a questionnaire administered in Casualty, (2) a quantified method of determining alcohol consumption during a subsequent ward dietetic assessment, (3) in relation to a biochemical definition (recent drinking and non-drinking), and a classification of (1) and (2) called, for the purposes of this thesis, 'alcohol abusers' and 'nonabusers'. Heavy, regular and recent drinkers and alcohol abusers tend to be male and younger than light, infrequent and nonrecent drinkers and nonabusers. Chapter 5 relates the nutritional status of those patients admitted acutely to hospital in relation to the groups defined in Chapter 4, Nutritional status is defined in terms of food intake, anthropometry, biochemical and haematological parameters. Different methods of defining alcohol use give rise to different patterns of nutritional impairment. Chapter 6 relates the nutritional status of those patients admitted acutely to hospital in relation to the presence or absence of an endoscopically defined site of upper gastrointestinal bleeding. A difference is seen between those bleeding from a Mailory-weiss tear and other sites of bleeding, similarly, biochemical differences in nutritional status emerge between those patients who presented in shock, and those who did not. Chapter 7 explores the relationships between biochemical markers of nutritional status and haemostatic variables in the groups of abusers/non-abusers, the various sites of primary bleeding/controls, and shock/non-shock. Serum copper appears to be related to altered haemostasis in a manner not apparently described elsewhere.

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Nodularia spumigena periodically proliferates to cause toxic algal blooms with some aquatic animals enduring and consuming high densities of the blue green algae or toxic lysis. N. spumigena contains toxic compounds such as nodularin and lipopolysaccharides. This current work investigates physiological effects of exposure from bloom conditions of N. spumigena cells and a post-bloom lysis. Biochemical and antioxidative biomarkers were comparatively studied over an acute 3-day exposure. In general, a post-bloom N. spumigena lysis caused opposite physiological responses to bloom densities of N. spumigena. Specifically, increases in glutathione (GSH) and glutathione peroxidase (GPx) and decreases in glutathione S-transferase (GST) were observed from the N. spumigena lysis. In contrast, N. spumigena cell densities decreased GSH and increased GST and lipid peroxidation (LPO) in mussels. Findings also suggest that at different stages of a toxic bloom, exposure may result in toxic stress to specific organs in the mussel.

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Natriuretic peptides are bioactive proteins. In plants, biochemical and physiological studies on these molecules has now revealed that they influence stomatal opening, cell volume and the activity of membrane pumps and their localisation within vascular tissues. Thus they have major roles in maintaining water and solute homeostasis.

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This project investigated how plants respond to invading pathogens using microscopic, biochemical and genetic approaches. The development of transgenic plants containing the green fluorescent protein cloned from jellyfish enabled a new approach to studying plant defence genes. In particular, the role and involvement of the plant gene PAL1 was analysed.

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In some patients with major depressive disorder (MDD), individual illness characteristics appear consistent with those of a neuroprogressive illness. Features of neuroprogression include poorer symptomatic, treatment and functional outcomes in patients with earlier disease onset and increased number and length of depressive episodes. In such patients, longer and more frequent depressive episodes appear to increase vulnerability for further episodes, precipitating an accelerating and progressive illness course leading to functional decline. Evidence from clinical, biochemical and neuroimaging studies appear to support this model and are informing novel therapeutic approaches. This paper reviews current knowledge of the neuroprogressive processes that may occur in MDD, including structural brain consequences and potential molecular mechanisms including the role of neurotransmitter systems, inflammatory, oxidative and nitrosative stress pathways, neurotrophins and regulation of neurogenesis, cortisol and the hypothalamic–pituitary–adrenal axis modulation, mitochondrial dysfunction and epigenetic and dietary influences. Evidence-based novel treatments informed by this knowledge are discussed.

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Exposure of fish to stressors can elicit biochemical and organismal changes at multiple levels of biological organization collectively known as stress responses. The organismal (plasma glucose and cortisol levels) and cellular (hepatic hsp70) stress responses in fish have been studied in several species, but little is known about sex-related differences in these responses. In this study, we exposed sexually immature juvenile chinook salmon (Oncorhynchus tshawytscha) to bleached kraft mill effluent (BKME: 0%, 1%, and 10% v/v) for 30 days and then measured components of their organismal and cellular stress responses. Males exposed to 1% BKME had higher levels of plasma glucose than females. Plasma cortisol levels were unaffected in females exposed to BKME, but males exposed to 10% BKME had significantly higher levels of plasma cortisol relative to non-exposed males. While exposure to BKME did not affect hsp70 levels in males, females exposed to 1% BKME had higher levels of hsp70 relative to non-exposed and 10% BKME groups. Within any given treatment, females had higher levels of hsp70 relative to males. This study demonstrates that sex-related differences exist in commonly used indicators of stress in fish, and points out the importance of considering the sex of the fish in stress research.

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The fabrication of tissue engineering scaffolds is a well-established field that has gained recent prominence for the in vivo repair of a variety of tissue types. Recently, increasing levels of sophistication have been engineered into adjuvant scaffolds facilitating the concomitant presentation of a variety of stimuli (both physical and biochemical) to create a range of favourable cellular microenvironments. It is here that self-assembling peptide scaffolds have shown considerable promise as functional biomaterials, as they are not only formed from peptides that are physiologically relevant, but through molecular recognition can offer synergy between the presentation of biochemical and physio-chemical cues. This is achieved through the utilisation of a unique, highly ordered, nano- to microscale 3-D morphology to deliver mechanical and topographical properties to improve, augment or replace physiological function. Here, we will review the structures and forces underpinning the formation of self-assembling scaffolds, and their application in vivo for a variety of tissue types.