93 resultados para erythrocyte lifespan


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The relationship life cycle has been central to relationship development literature and has largely assumed that relationship development is an evolutionary linear process. There has generally been limited discussion of the fact that over a relationship’s lifespan it may in fact strengthen, weaken, and even become inactive, which is not the same as relationship failure. The paper proposes a dynamic model of relationship development that includes relationship inactivity as a significant phase.

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Merozoite surface protein 8 (MSP8) has shown promise as a vaccine candidate in the Plasmodium yoelii rodent malaria model and has a proposed role in merozoite invasion of erythrocytes. However, the temporal expression and localisation of MSP8 are unusual for a merozoite antigen. Moreover, in Plasmodium falciparum the MSP8 gene could be disrupted with no apparent effect on in vitro growth. To address the in vivo function of full-length MSP8, we truncated MSP8 in the rodent parasite Plasmodium berghei. PbΔMSP8 disruptant parasites displayed a normal blood-stage growth rate but no increase in reticulocyte preference, a phenomenon observed in P. yoelii MSP8 vaccinated mice. Expression levels of erythrocyte surface antigens were similar in P. berghei wild-type and PbΔMSP8-infected erythrocytes, suggesting that a parasitophorous vacuole function for MSP8 does not involve global trafficking of such antigens. These data demonstrate that a full-length membrane-associated form of PbMSP8 is not essential for blood-stage growth.

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"The incidence and prevalence of diabetes is increasing globally, and most health professionals are likely to care for people with diabetes. In such cases they may often find that they have to make clinical decisions without expert support, which can be difficult for both patient and carer."
"Managing Clinical Problems in Diabetes provides this support by exploring common clinical problems in diabetes care, and providing practical solutions based on evidence and the clinical experience of diabetes educators, endocrinologists, general practitioners, and other health professionals who encounter such problems on a daily basis. Each chapter begins with an introductory section presenting an overview of the management of diabetes, including short- and long- tern complications and management targets across the lifespan. The authors then pose commonly encountered diabetes management problems, developing comprehensive responses from a range of relevant health professionals who each provide management suggestions from their area of practice." "Managing Clinical Problems in Diabetes is a vital resource for health professionals involved in the provision of care for people with diabetes."--BOOK JACKET.

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Learning objectives: To contribute to mental health nurses understanding and knowledge of mental health triage practice through the presentation of current research findings on the topic. A specific focus of the paper will be an overview of how mental health triage practice differs across the lifespan.

Mental health triage is a highly specialised area of clinical practice for mental health nursing that is in its infancy in terms of articulating practice and theory. This paper addresses the conference theme of mental health nursing practice: new roles, new challenges by presenting the findings of a qualitative research project that investigated mental health triage/duty/intake practices across the five community mental health agencies of The Alfred Hospital, Melbourne. The overall aim of the project was to work collaboratively with clinicians to further develop the quality and consistency of mental health triage, duty, and intake clinical practice across all arms of Alfred Psychiatry. The project was designed to facilitate the expansion of the mental health triage knowledge base, and thus contribute to the further development of triage clinical practice. One of the unique aspects of the project was its triangulation across the adult triage service (acute), the two Continuing Care Teams, and the specialist psychiatric services such as the Child and Adolescent Mental Health Service, the Homeless and Outreach Psychiatric Service, and the Mobile Aged Psychiatric Service. The project employed focus group method to collect in-depth, qualitative data. A series of nine focus groups were conducted at each site, which concentrated on eliciting data on the core areas of mental health triage practice such as telephone consultation skills, mental status examination, risk assessment, decision-making, negotiation, crisis assessment, secondary consultation, and documentation. The investigation produced a considerable amount of high quality, in-depth data that was analysed using content analysis methods. The project produced data that will make a significant contribution to the expanding body of knowledge on mental health triage practice.

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The world was captivated when footage of a badly burnt koala drinking water from a Victorian firefighter's bottle was uploaded to You Tube in February 2009. When the story of "Sam the Koala" was adopted by the mainstream media, recombinant themes were used to construct her story - from heroism and patriotism to villain vs victim and romance. While scholars have examined the changing role of the journalist in a converged world and the rise of "soft" news, this paper focuses on the way journalists create disjointed narratives around You Tube footage to extend a story s lifespan. We call these new narrative forms "fractured fairy tale news" to describe this emerging phenomenon of convergence culture. Further, we suggest that news media exploit the YouTube community for their own commercial gain and conclude that the fractured fairy tale style is a poor vehicle for the future of news.

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The maintenance of functional physical fitness across the lifespan depends upon the presence or absence of disease, injury, and the level of habitual physical activity. The prevalence of sedentariness rises with increasing age culminating in 31% of elderly women being classified as leading a sedentary lifestyle. Exercise prescription that involves easily accomplished physical activity may result in the maintenance of mobility into old age through a reduction in the risk of premature death and disablement from cardiovascular disease and a reduction in the risk of falls and injuries from falls. It may be that short bouts of physical activity are more appealing to the sedentary and to those in full time employment than longer bouts, and it may be that short bouts of exercise, performed three times per day, can improve physical fitness. The purpose of this study was therefore to examine the problem: Does exercise session duration, initial cardiovascular fitness, and age group effect changes in functional physical fitness in sedentary women training for strength, flexibility and aerobic fitness? Twenty-three, sedentary women aged between 19 and 54 years who were employed at a major metropolitan hospital undertook six weeks of moderate intensity physical activity in one of two training groups. Participants were randomly allocated to either short duration (3 x 10 minute), or long duration (30 minute), exercise groups. The 3 x 10 minute group (n=13), participated in three, 10 minute sessions per day separated by at least 2 hours, 3 days per week. The 30 minute group (n=10), participated in three 30 minute sessions per week. The total amount of work was similar, with an average of 129 and 148 kcal training day for the 3 x 10 minute and 30 minute groups, respectively. The training program incorporated three walking and stair climbing courses for aerobic conditioning, a series of eleven static stretches for joint flexibility, and isotonic and isometric strength exercises for lower and upper body muscular strength. Measures of functional strength, functional flexibility and cardiovascular fitness were assessed prior to training, and immediately following the six week exercise program. A two way analysis of variance (Group x Time) was used to examine the effect of training and group on the dependent variables. The level of significance, 0.05 was adopted for all statistical tests. Mean hand grip strength showed for both groups no significant change over time for the 3 x 10 minute group (30.7kg to 31.7kg) and 30 minute group (30.2kg to 32.4kg). Leg strength showed a trend for improvement (p=0.098) in both the 3 x 10 minute and 30 minute training groups representing a 15% and 18% improvement, respectively. Combined right and left neck rotation significantly improved in the 3 x 10 minute group (82.8° to 92.0°) and 30 minute group (82.5° to 91.5°). Wrist flexion and extension improved significantly in 3 out of the 4 measurements. Left wrist flexion improved significantly by an average of 7.0% for the 3 x 10 minute and 4.9% for the 30 minute group. Right and left wrist extension improved significantly in the 3 x 10 minute and 30 minute training groups (5.9% and 6.8%, respectively). Hip and spine flexibility improved 3.4cm (35.2cm to 38.6cm) in the 3 x 10 minute group, and 6.6cm (37.4cm to 44.0cm) in the 30 minute group. There was a significant improvement in cardiovascular fitness for both groups representing a 22% improvement in the 3 x 10 minute group (27.2 to 33.2 ml kg min), and a 25% improvement in the 30 minute group (27.5 to 34.4 ml -kg min). No significant difference was shown in the degree of improvement in cardiovascular fitness over six weeks of training for subjects of either low or moderate initial aerobic fitness. Grip strength showed no significant changes over time for either the young-aged (19-35 years) or middle-aged (36-54 years) groups. Leg strength showed a trend for improvement (p=0.093) in the young-aged group (63.5kg to 71.9kg) and middle-aged group (69.3kg to 85.8kg). Neck rotation flexibility improved a similar amount in both the young and middle aged groups representing an improvement of 9.9° and 8.0° respectively. There was significant improvement in two of the four measures of wrist flexibility. Hip and spine flexibility was significantly greater in the young-aged group compared to the middle-aged group (38.5cm and 30.7cm, respectively). There was a significant improvement in hip and spine flexibility over the six week training program representing an increase in reach of 6.5cm for the young age group and 4.9cm for the older group. The middle-aged subjects had significantly lower cardiovascular fitness than their younger peers, scoring 22.8 and 30.7 ml -kg min, respectively. Cardiovascular fitness improved a similar amount in both age groups representing a significant improvement of 23.8% and 28.1% for the younger-aged and middle-aged subjects, respectively. The findings of this study suggest that short bouts of exercise may be equally as effective as longer bouts of exercise for improving the flexibility and cardiovascular components of functional physical fitness in sedentary young and middle aged women. Additionally short bouts of exercise may be more attractive than longer bouts of exercise for the beginning exerciser as they may more easily fit into the busy lifestyle encountered by many people in today's society. Sedentary young and middle-aged women should benefit from static flexibility exercises designed to improve and/or maintain functional flexibility and thus maintain mobility and reduce the incidence of muscular injury. Regular, brisk walking, incorporating some stair climbing, is likely to be beneficial in improving cardiovascular health and perhaps also in improving leg strength, thereby helping to improve and maintain functional physical fitness for both young and middle-aged sedentary women.

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Australia's ageing population created challenges for maintaining well-being and combating social isolation. Older Australians frequently rely on community arts organizations to enhance quality of life, specifically in health, happiness and community. Arts engagement takes place in many different contexts, from formal to informal and throughout the lifespan of the individual. Culture shapes the way in which we age and cultural identity is celebrated through the arts. This study will explore ageing and cultural diversity within Australian society through an examination of community arts engagement, specifically a community choir in Melbourne, Victoria, Australia. Much previous research concerning music engagement by older people has focused on its therapeutic applications, but there have been less attention given to healthy older people still living in communities. This paper reports on how music engagement can facilitate successful ageing be encouraging a sense of community, enhancing well-being and supporting cultural identity.

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The virulence of the malaria parasite, Plasmodium falciparum, is due in large part to the way in which it modifies the membrane of its erythrocyte host. In this work we have used confocal microscopy and fluorescence recovery after photo-bleaching to examine the lateral mobility of host membrane proteins in erythrocytes infected with P falciparum at different stages of parasite growth. The erythrocyte membrane proteins band 3 and glycophorin show a marked decrease in mobility during the trophozoite stage of growth. Erythrocytes infected with a parasite strain that does not express the knob-associated histidine-rich protein show similar effects, indicating that this parasite protein does not contribute to the immobilization of the host proteins. Erythrocytes infected with ring-stage parasites exhibit intermediate mobility indicating that the parasite is able to modify its host prior to its active feeding stage.

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The proliferation of the malaria parasite Plasmodium falciparum within the human host is dependent upon invasion of erythrocytes. This process is accomplished by the merozoite, a highly specialized form of the parasite. Secretory organelles including micronemes and rhoptries play a pivotal role in the invasion process by storing and releasing parasite proteins. The mechanism of protein sorting to these compartments is unclear. Using a transgenic approach we show that trafficking of the most abundant micronemal proteins (members of the EBL-family: EBA-175, EBA-140/BAEBL, and EBA-181/JSEBL) is independent of their cytoplasmic and transmembrane domains, respectively. To identify the minimal sequence requirements for microneme trafficking, we generated parasites expressing EBAGFP chimeric proteins and analyzed their distribution within the infected erythrocyte. This revealed that: (i) a conserved cysteine-rich region in the ectodomain is necessary for protein trafficking to the micronemes and (ii) correct sorting is dependent on accurate timing of expression.

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One of the key processes in the pathobiology of the malaria parasite is the invasion and subsequent modification of the human erythrocyte. In this complex process, an unknown number of parasite proteins are involved, some of which are leading vaccine candidates. The majority of the proteins that play pivotal roles in invasion are either stored in the apical secretory organelles or located on the surface of the merozoite, the invasive stage of the parasite. Using transcriptional and structural features of these known proteins, we performed a genomewide search that identified 49 hypothetical proteins with a high probability of being located on the surface of the merozoite or in the secretory organelles. Of these candidates, we characterized a novel leucine zipper-like protein in Plasmodium falciparum that is conserved in Plasmodium spp. This protein is expressed in late blood stages and localizes to the rhoptries of the parasite. We demonstrate that this Plasmodium sp.-specific protein has a high degree of conservation within field isolates and that it is refractory to gene knockout attempts and thus might play an important role in invasion.

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Osmiophilic bodies are membrane-bound vesicles, found predominantly in Plasmodium female gametocytes, that become progressively more abundant as the gametocyte reaches full maturity. These vesicles lie beneath the subpellicular membrane of the gametocyte, and the release of their contents into the parasitophorous vacuole has been postulated to aid in the escape of gametocytes from the erythrocyte after ingestion by the mosquito. Currently, the only protein known to be associated with osmiophilic bodies in Plasmodium falciparum is Pfg377, a gametocyte-specific protein expressed at the onset of osmiophilic body development. Here we show by targeted gene disruption that Pfg377 plays a fundamental role in the formation of these organelles, and that female gametocytes lacking the full complement of osmiophilic bodies are significantly less efficient both in vitro and in vivo in their emergence from the erythrocytes upon induction of gametogenesis, a process whose timing is critical for fertilization with the short-lived male gamete. This reduced efficiency of emergence explains the significant defect in oocyst formation in mosquitoes fed blood meals containing Pfg377-negative gametocytes, resulting in an almost complete blockade of infection.

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Antibodies from malaria-exposed individuals can agglutinate merozoites released from Plasmodium schizonts, thereby preventing them from invading new erythrocytes. Merozoite coat proteins attached to the plasma membrane are major targets for host antibodies and are therefore considered important malaria vaccine candidates. Prominent among these is the abundant glycosylphosphatidylinositol (GPI)-anchored merozoite surface protein 1 (MSP1) and particularly its C-terminal fragment (MSP1(19)) comprised of two epidermal growth factor (EGF)-like modules. In this paper, we revisit the role of agglutination and immunity using transgenic fluorescent marker proteins. We describe expression of heterologous MSP1(19)'miniproteins' on the surface of Plasmodium falciparum merozoites. To correctly express these proteins, we determined that GPI-anchoring and the presence of a signal sequence do not allow default export of proteins from the endoplasmic reticulum to merozoite surface and that extra sequence elements are required. The EGFs are insufficient for correct trafficking unless they are fused to additional residues that normally reside upstream of this fragment. Antibodies specifically targeting the surface-expressed miniprotein can inhibit erythrocyte invasion in vitro despite the presence of endogenous MSP1. Using a line expressing a green fluorescent protein-MSP1 fusion protein, we demonstrate that one mode of inhibition by antibodies targeting the MSP1(19) domain is the rapid agglutinating of merozoites prior to erythrocyte attachment.

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Background
Developing effective prevention and intervention programs for the formative preschool years is seen as an essential step in combating the obesity epidemic across the lifespan. The overall goal of the current project is to measure the effectiveness of a healthy eating and childhood obesity prevention intervention, the MEND (Mind Exercise Nutrition Do It!) program that is delivered to parents of children aged 2-4 years.

Methods/Design
This randomised controlled trial will be conducted with 200 parents and their 2-4 year old children who attend the MEND 2-4 program in metropolitan and regional Victoria. Parent-child dyads will attend ten 90-minute group workshops. These workshops focus on general nutrition, as well as physical activity and behaviours. They are typically held at community or maternal and child health centres and run by a MEND 2-4 trained program leader. Child eating habits, physical activity levels and parental behaviours and cognitions pertaining to nutrition and physical activity will be assessed at baseline, the end of the intervention, and at 6 and 12 months post the intervention. Informed consent will be obtained from all parents, who will then be randomly allocated to the intervention or wait-list control group.

Discussion
Our study is the first RCT of a healthy eating and childhood obesity prevention intervention targeted specifically to Australian parents and their preschool children aged 2-4 years. It responds to the call by experts in the area of childhood obesity and child health that prevention of overweight in the formative preschool years should focus on parents, given that parental beliefs, attitudes, perceptions and behaviours appear to impact significantly on the development of early overweight. This is 'solution-oriented' rather than 'problem-oriented' research, with its focus being on prevention rather than intervention. If this is a positive trial, the MEND2-4 program can be implemented as a national program.

Trial Registration
Australian New Zealand Clinical Trials Registry ACTRN12610000200088

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It is somewhat paradoxical that the malaria parasite’s survival strategy involves spending almost all of its blood-stage existence residing behind a two-membrane barrier in a host red blood cell, yet giving considerable attention to exporting parasite-encoded proteins back across these membranes. These exported proteins are thought to play diverse roles and are crucial in pathogenic processes, such as re-modelling of the erythrocyte cytoskeleton and mediating the export of a major virulence protein known as Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), and in metabolic processes such as nutrient uptake and solute exchange. Despite these varied roles most exported proteins have at least one common link; they share a trafficking pathway that begins with entry into the endoplasmic reticulum and concludes with passage across the vacuole membrane via a proteinaceous translocon known as the Plasmodium translocon of exported proteins (PTEX). In this commentary we review recent advances in our understanding of this export pathway and suggest several models by which different aspects of the process may be interconnected.

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Plasmodium falciparum causes the virulent form of malaria and disease manifestations are linked to growth inside infected erythrocytes. To survive and evade host responses the parasite remodels the erythrocyte by exporting several hundred effector proteins beyond the surrounding parasitophorous vacuole membrane. A feature of exported proteins is a pentameric motif (RxLxE/Q/D) that is a substrate for an unknown protease. Here we show that the protein responsible for cleavage of this motif is plasmepsin V (PMV), an aspartic acid protease located in the endoplasmic reticulum. PMV cleavage reveals the export signal (xE/Q/D) at the amino terminus of cargo proteins. Expression of an identical mature protein with xQ at the N terminus generated by signal peptidase was not exported, demonstrating that PMV activity is essential and linked with other key export events. Identification of the protease responsible for export into erythrocytes provides a novel target for therapeutic intervention against this devastating disease.