RESUMO
This study aims to provide practical insights for developing trauma-informed interaction strategies between service providers and participants in homeless service organizations (HSOs). Twelve providers and 17 participants were interviewed for a qualitative study on trauma-informed care (TIC) within an HSO. Thematic analysis revealed six themes regarding provider approaches to TIC interactions with participants: provide a sounding board, promote safety, foster understanding and respect, build relationships and trust, facilitate connection to services, and ensure flexibility in service provision. Participants noted three themes regarding their views of TIC interactions with providers: possess education and experience, build relationships and trust, and demonstrate supportive interpersonal styles. This study describes the application of TIC within an HSO, emphasizing the importance of supportive, positive interactions that promote understanding, respect, and trust. It highlights key factors in service provision. The findings expand our understanding of TIC implementation in HSOs and suggest areas for improvement.
Assuntos
Pessoas Mal Alojadas , Humanos , Pesquisa Qualitativa , Atitude do Pessoal de Saúde , EscolaridadeRESUMO
In 2006, the European Federation of Organisations for Medical Physics (EFOMP) adopted the "Malaga Declaration". The declaration asserted the fundamental role of Medical Physics professionals in the radiation protection of patients, workers, general public, carers and comforters and research participants in hospitals. However, since that time the Medical Physics profession has evolved in Europe and new regulations and documentation have been issued, such as directive 2013/59/Euratom and the "European Guidelines on Medical Physics Expert" (RP174). EFOMP has published updated core-curricula and strived towards the recognition of the profession at the European level. In view of this, an update of the original Malaga Declaration was deemed necessary, to define the future vision that will guide the actions of the Federation in the years to come. This Declaration, which has been approved by the national member organizations of EFOMP in April 2023, is much broader than the original Malaga version. This is expected considering the rapid evolution of medical device technology over the last 17 years. The Radiation Protection Expert in hospital settings should be an MPE, since the latter has the highest level of radiation protection knowledge and training. Given the passion and energy that animated the debate, which led to the updating of the Malaga Declaration, we are confident that it represents a solid basis for the development of our profession in Europe which is in consonance with the aspirations of us all.
Assuntos
Física Médica , Proteção Radiológica , Humanos , Física Médica/educação , Europa (Continente) , Currículo , União EuropeiaRESUMO
The potential benefits of adding raw, non-food, lignocellulosic plant material as a carbon source for mixotrophic growth of microalgae have previously been demonstrated. This approach has advantages over using traditional carbon sources like glucose or acetate due to wide-spread plant biomass availability and substrate recalcitrance to bacterial contamination. Here, we report the overall growth characteristics and explore the metabolic patterns of Scenedesmus obliquus cultured in the presence raw plant substrate. An initial screen of plant substrate candidates showed an increase in specific growth rate and biomass accumulation when S. obliquus was cultured in the presence of switchgrass or yard waste compared to media alone. We observed a near doubling of microalgal dry weight when S. obliquus was grown with 0.2% (w/v) switchgrass under ambient CO2. Scanning electron microscopy (SEM) of corn stem after S. obliquus cultivation exhibited substantial phloem degradation. Transcriptomic analyses of S. obliquus during mid- and late-log phase growth revealed a dynamic metabolic landscape within many KEGG pathways. Notably, differential expression was observed for several potential glycosyl hydrolases. We also investigated the influence of switchgrass on the growth of S. obliquus at 50 L volume in mini raceway ponds to determine the scalability of this approach.
RESUMO
Dupuytren's disease is a progressive fibrotic condition of the hand that causes contracture of fingers in later stages. Our previous in vitro studies suggest that the transformation of fibroblasts to myofibroblasts induced by transforming growth factor-beta can be inhibited by the addition of the antifibrotic drug, pirfenidone (PFD). We hypothesize that the local delivery of PFD directly to nodules can potentially prevent the progression to cords and, furthermore, that injection of PFD after the resection of cords can limit the recurrence of the disease. The purpose of this research was to develop a PFD injectable solution and to assess its safety in mice. Based on preformulation observations, a sterile solution containing up to 8 mg/0.4 mL of PFD was prepared in a phosphate buffer with and without 15%v/v N-methyl-2-pyrrolidone. Accelerated stability studies suggested that the product should be kept at refrigerated temperature (2-8 °C) for long-term storage. Safety studies involving subcutaneous administration to mice showed that 2-4 mg of PFD in 0.4 mL aqueous buffer did not elicit a significant inflammatory reaction. However, 4 mg PFD in 0.4 mL (FB) of buffer: NMP cosolvent system led to a significant increase in the influx of inflammatory cells and 8 mg PFD (FA) in the cosolvent system was lethal to the animals.
Assuntos
Contratura de Dupuytren , Animais , Contratura de Dupuytren/tratamento farmacológico , Fibroblastos , Camundongos , Piridonas/farmacologiaRESUMO
Cutaneous thermal injuries from burns/explosives are a major cause of morbidity and mortality and represent a monumental burden on our current health care system. Injury severity is predominantly due to potentially lethal sepsis caused by multidrug-resistant (MDR) bacteria such as Pseudomonas aeruginosa (MDR-PA). Thus, there is a critical need to develop novel and effective antimicrobials for the (i) prevention, (ii) treatment, and (iii) healing of such wounds that are complicated by MDR-P. aeruginosa and other bacterial infections. AB569 is a novel bactericidal tandem consisting of acidified NaNO2 (A-NO2-) and Na2-EDTA. Here, we first show that AB569 acts synergistically to kill all human burn wound strains of P. aeruginosa in vitro. This was found to be due, in part, to the generation of A-NO2--mediated nitric oxide (NO) formation coupled with the metal chelating properties of Na2-EDTA. Using a murine scald burn wound model of P. aeruginosa infection, an AB569-Solosite gel formulation eradicated all bacteria. Futher, we also demonstrate enhanced AB569-mediated wound healing by not only accelerating wound contraction, but also by reducing levels of the proinflammatory cytokines interleukin-6 (IL-6) and IL-1ß while increasing the levels of anti-inflammatory cytokine, IL-10, and granulocyte-colony-stimulating factor (G-CSF). We also observed better epidermal restoration in AB569-treated wounds. Taken together, we conclude that this study provides solid foundational evidence that AB569 can be used topically to treat highly problematic dermal insults, including wound, burn, blast, and likely, diabetic infections in civilian and military populations, and help relieve the economical burden that MDR organisms have on the global health care system.
Assuntos
Antibacterianos/farmacologia , Queimaduras/tratamento farmacológico , Ácido Edético/farmacologia , Nitritos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Cicatrização/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Queimaduras/complicações , Queimaduras/microbiologia , Colágeno/genética , Modelos Animais de Doenças , Ácido Edético/uso terapêutico , Géis , Óxido Nítrico/biossíntese , Nitritos/uso terapêutico , Infecções por Pseudomonas/tratamento farmacológicoRESUMO
One of the major factors limiting biomass productivity in algae is the low thermodynamic efficiency of photosynthesis. The greatest thermodynamic inefficiencies in photosynthesis occur during the conversion of light into chemical energy. At full sunlight the light-harvesting antenna captures photons at a rate nearly 10 times faster than the rate-limiting step in photosynthetic electron transport. Excess captured energy is dissipated by non-productive pathways including the production of reactive oxygen species. Substantial improvements in photosynthetic efficiency have been achieved by reducing the optical cross-section of the light-harvesting antenna by selectively reducing chlorophyll b levels and peripheral light-harvesting complex subunits. Smaller light-harvesting antenna, however, may not exhibit optimal photosynthetic performance in low or fluctuating light environments. We describe a translational control system to dynamically adjust light-harvesting antenna sizes for enhanced photosynthetic performance. By expressing a chlorophyllide a oxygenase (CAO) gene having a 5' mRNA extension encoding a Nab1 translational repressor binding site in a CAO knockout line it was possible to continuously alter chlorophyll b levels and correspondingly light-harvesting antenna sizes by light-activated Nab1 repression of CAO expression as a function of growth light intensity. Significantly, algae having light-regulated antenna sizes had substantially higher photosynthetic rates and two-fold greater biomass productivity than the parental wild-type strains as well as near wild-type ability to carry out state transitions and non-photochemical quenching. These results have broad implications for enhanced algae and plant biomass productivity.
Assuntos
Clorófitas/metabolismo , Complexos de Proteínas Captadores de Luz/fisiologia , Fotossíntese , Biomassa , Clorofila/metabolismo , Clorófitas/crescimento & desenvolvimento , Clorófitas/fisiologia , Luz , Complexos de Proteínas Captadores de Luz/metabolismo , Fotossíntese/fisiologia , Plantas Geneticamente ModificadasRESUMO
Pericytes are cells that reside adjacent to microvasculature and regulate vascular function. Pericytes gained great interest in the field of wound healing and regenerative medicine due to their multipotential fate and ability to enhance angiogenesis. In burn wounds, scarring and scar contractures are the major pathologic feature and cause loss of mobility. The present study investigated the influence of burn wound environment on pericytes during wound healing. Pericytes isolated from normal skin and tangentially excised burn eschar tissues were analyzed for differences in gene and protein expression using RNA-seq., immunocytochemistry, and ELISA analyses. RNA-seq identified 443 differentially expressed genes between normal- and burn eschar-derived pericytes. Whereas, comparing normal skin pericytes to normal skin fibroblasts identified 1021 distinct genes and comparing burn eschar pericytes to normal skin fibroblasts identified 2449 differential genes. Altogether, forkhead box E1 (FOXE1), a transcription factor, was identified as a unique marker for skin pericytes. Interestingly, FOXE1 levels were significantly elevated in burn eschar pericytes compared to normal. Additionally, burn wound pericytes showed increased expression of profibrotic genes periostin, fibronectin, and endosialin and a gain in contractile function, suggesting a contribution to scarring and fibrosis. Our findings suggest that the burn wound environment promotes pericytes to differentiate into a myofibroblast-like phenotype promoting scar formation and fibrosis.
RESUMO
The ovulatory homolog model of female orgasm posits that the neuro-endocrine mechanisms underlying female orgasm evolved from and are homologous to the mechanisms mediating copulation-induced ovulation in some mammals. This model predicts that pharmacological agents that affect human orgasm, such as fluoxetine, should also affect ovulation in animals with copulation-induced ovulation, such as rabbits. We tested this prediction by treating rabbits with daily doses of fluoxetine for 2 wk and found that fluoxetine treatment reduces the number of ovulations postcopulation by 30%. In a second experiment we tested whether this result was mediated by an effect on the brain or via peripheral serotonin functions. We treated animals with fluoxetine and induced ovulation with a single injection of human chorionic gonadotropin. In this experiment ovulation rate was nominally reduced by only 8%, which is statistically not significant. We conclude that the effect of fluoxetine on copulation-induced ovulation rate supports the ovulatory homolog model of female orgasm, suggesting that female orgasm has very deep evolutionary roots among the early eutherian mammals.
Assuntos
Evolução Biológica , Gonadotropina Coriônica/farmacologia , Fluoxetina/farmacologia , Ovulação/efeitos dos fármacos , Animais , Gonadotropina Coriônica/administração & dosagem , Copulação/fisiologia , Feminino , Fluoxetina/administração & dosagem , Masculino , Ovulação/fisiologia , Coelhos , Substâncias para o Controle da Reprodução/administração & dosagem , Substâncias para o Controle da Reprodução/farmacologia , Inibidores Seletivos de Recaptação de Serotonina/administração & dosagem , Inibidores Seletivos de Recaptação de Serotonina/farmacologiaRESUMO
PURPOSE: The proportion of patients with advanced cancer who receive outpatient specialty palliative care (OSPC) is as low as 2.0%. Improved understanding of the system-level factors influencing use of OSPC could inform adaptations to the delivery of palliative care to maximize access. We examined associations between OSPC use among patients with advanced solid tumors and oncology-OSPC clinic colocation and patient travel time to an OSPC clinic. PATIENTS AND METHODS: We conducted a retrospective cohort study of patients with advanced solid tumors receiving oncologic treatment between January 1 and December 31, 2016, within a comprehensive cancer center network with well-established, oncology-specific OSPC clinics. Multivariable logistic regression analysis was used to evaluate the associations of clinic colocation and geographic access with OSPC use. RESULTS: Of 9,485 patients with advanced solid tumors, 478 (5.0%) received OSPC services in 2016. After controlling for age, sex, marital status, cancer type, insurance, treatment intent, and illness severity, patients whose oncologist practices were colocated with OSPC clinics were more likely to use OSPC (odds ratio [OR], 19.2; 95% CI, 14.1 to 26.2). Compared with patients who lived > 90 minutes from an OSPC clinic, patients with travel times of < 30 minutes (OR, 3.2; 95% CI, 2.2 to 4.6) and 31 to 60 minutes (OR, 2.4; 95% CI, 1.6 to 3.6) were also more likely to use OSPC. CONCLUSION: Among patients with advanced solid tumors, colocation of oncology and OSPC clinics and shorter patient travel time were associated with greater odds of using OSPC. Future efforts to increase OSPC use in this population should consider clinic colocation and travel burden.
Assuntos
Oncologia , Neoplasias/terapia , Cuidados Paliativos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Pacientes Ambulatoriais , Estudos Retrospectivos , Fatores de Tempo , ViagemRESUMO
Despite clear clinical benefit and guideline recommendations for predictive biomarker testing and subsequent first-line targeted therapy treatment in patients with non-small cell lung cancer (NSCLC), there is evidence that testing has not been widely embraced in the clinical setting. This study uses clinical pathways to understand biomarker testing patterns and ensuing first-line treatment decisions. Data of patients with metastatic NSCLC were analyzed for testing rates and treatment selection at 7 cancer programs using data input by providers into the pathways software. Findings were analyzed by type of provider (community or academic). Among providers using clinical pathways, biomarker testing rates were high and appropriate selection of targeted therapy was observed. Clinical pathways can act as a tool to assist oncology practices to promote testing of key biomarkers and subsequent selection of appropriate therapy.
RESUMO
A current need in the global effort to eliminate lymphatic filariasis (LF) is the availability of reliable diagnostic tools that can be used to guide programmatic decisions, especially decisions made in the final stages of the program. This study conducted in The Gambia aimed to assess antifilarial antibody levels among populations living in historically highly LF-endemic areas and to evaluate the use of serologic tools to confirm the interruption of LF transmission. A total of 2,612 dried blood spots (DBSs) collected from individuals aged 1 year and above from 15 villages were tested for antibodies to Wb123 by enzyme-linked immunosorbent assay (ELISA). A subset of DBS (N = 599) was also tested for antibodies to Bm14 by ELISA. Overall, the prevalence of Wb123 was low (1.5%, 95% confidence interval [CI] 1.1-2.1%). In 7 of 15 villages (46.7%), there were no Wb123-positive individuals identified. Individuals with positive responses to Wb123 ranged in age from 3 to 100 years. Overall, Bm14 prevalence was also low (1.5%, 95% CI 0.7-2.8%). Bm14 positivity was significantly associated with older age (P < 0.001). The low levels of antibody responses to Wb123 observed in our study strongly suggest that sustainable LF transmission has likely ceased in The Gambia. In addition, our results support the conclusion that serologic tools can have a role in guiding programmatic decision making and supporting surveillance.
Assuntos
Anticorpos Anti-Helmínticos/imunologia , Filariose Linfática/epidemiologia , Ensaio de Imunoadsorção Enzimática/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Erradicação de Doenças , Filariose Linfática/diagnóstico , Filariose Linfática/imunologia , Filariose Linfática/prevenção & controle , Feminino , Gâmbia/epidemiologia , Humanos , Lactente , Masculino , Administração Massiva de Medicamentos , Pessoa de Meia-Idade , Adulto JovemRESUMO
PURPOSE: Via Pathways (clinical pathways for cancer) provide evidence-based guidance for specific patient presentations based on the merit of efficacy, then toxicity, and finally cost (if efficacy and toxicity are comparable). We evaluated the impact of a change to the guidance in the metastatic colorectal cancer (mCRC) setting across two large, integrated health networks. METHODS: Cetuximab and panitumumab were determined to have equal efficacy in the treatment of mCRC with no significant difference in toxicity based on recent data from key clinical studies. A cost analysis using Centers for Medicare and Medicaid Services average sales data determined a cost advantage for panitumumab. A substitution of panitumumab for cetuximab in the clinical pathway for all mCRC lines of therapy was initiated as of August 2014. RESULTS: In the preimplementation period, 86 (93.5%) and six (6.5%) treatment selections were for cetuximab and panitumumab, respectively. After the pathway change was implemented, 13 (18.1%) and 59 (81.9%) treatment selections were for cetuximab and panitumumab, respectively. The change in prescribing habits was rapidly altered by the pathway change. The estimated annualized cost savings for the two health networks resulting from the response to the pathway change was $711,021. CONCLUSION: This study demonstrates that clinical pathways can act as a tool to assist oncology practices in decreasing costs and quickly responding to changing treatment paradigms by providing clinicians with consensus-driven treatment recommendations that incorporate the most up-to-date clinical trial results, toxicity considerations, and regimen cost information.
Assuntos
Neoplasias Colorretais/epidemiologia , Procedimentos Clínicos , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/uso terapêutico , Tomada de Decisão Clínica , Neoplasias Colorretais/patologia , Neoplasias Colorretais/terapia , Gerenciamento Clínico , Feminino , Custos de Cuidados de Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Terapia de Alvo Molecular , Metástase Neoplásica , Qualidade da Assistência à SaúdeRESUMO
OBJECTIVE: To differentiate exposure to the newly introduced chikungunya virus from exposure to endemic dengue virus and other pathogens in Haiti. METHODS: We used a multiplex bead assay to detect immunoglobulin G (IgG) responses to a recombinant chikungunya virus antigen, two dengue virus-like particles and three recombinant Plasmodium falciparum antigens. Most (217) of the blood samples investigated were collected longitudinally, from each of 61 children, between 2011 and 2014 but another 127 were collected from a cross-sectional sample of children in 2014. FINDINGS: Of the samples from the longitudinal cohort, none of the 153 collected between 2011 and 2013 but 78.7% (48/61) of those collected in 2014 were positive for IgG responses to the chikungunya virus antigen. In the cross-sectional sample, such responses were detected in 96 (75.6%) of the children and occurred at similar prevalence across all age groups. In the same sample, responses to malarial antigen were only detected in eight children (6.3%) but the prevalence of IgG responses to dengue virus antigens was 60.6% (77/127) overall and increased steadily with age. Spatial analysis indicated that the prevalence of IgG responses to the chikungunya virus and one of the dengue virus-like particles decreased as the sampling site moved away from the city of Léogâne and towards the ocean. CONCLUSION: Serological evidence indicates that there had been a rapid and intense dissemination of chikungunya virus in Haiti. The multiplex bead assay appears to be an appropriate serological platform to monitor the seroprevalence of multiple pathogens simultaneously.
Assuntos
Febre de Chikungunya , Dengue , Exposição Ambiental , Malária , Adolescente , Febre de Chikungunya/diagnóstico , Febre de Chikungunya/epidemiologia , Vírus Chikungunya/isolamento & purificação , Criança , Pré-Escolar , Estudos Transversais , Dengue/diagnóstico , Dengue/epidemiologia , Exposição Ambiental/estatística & dados numéricos , Feminino , Haiti/epidemiologia , Humanos , Estudos Longitudinais , Malária/diagnóstico , Malária/epidemiologia , Masculino , Plasmodium falciparum/isolamento & purificaçãoRESUMO
AIMS AND OBJECTIVES: To determine the changes in symptoms experienced by rectal cancer patients during preoperative chemoradiotherapy, with a specific focus on fatigue and to explore how symptoms impact the quality of life. BACKGROUND: Rectal cancer continues to be a healthcare issue internationally, despite advances in management strategies, which includes the administration of preoperative chemoradiotherapy to improve locoregional control. It is known that this treatment may cause adverse effects; however, there is a paucity of literature that specifically examines fatigue, symptoms and quality of life in this patient cohort. DESIGN: A prospective, quantitative correlational design using purposive sampling was adopted. METHODS: Symptoms and quality of life were measured with validated questionnaires in 35 patients at four time points. RESULTS: Symptoms that changed significantly over time as examined using rm-anova include fatigue, bowel function issues, nutritional issues, pain, dermatological issues and urinary function issues. Findings indicate that fatigue leads to poorer quality of life, with constipation, bloating, stool frequency, appetite loss, weight worry, nausea and vomiting, dry mouth and pain also identified as influencing factors on quality of life. CONCLUSION: Findings have highlighted the importance of thorough symptom assessment and management of patients receiving preoperative chemoradiotherapy, particularly midway through treatment, in order to optimise quality of life and minimise interruptions to treatment. RELEVANCE TO CLINICAL PRACTICE: Close monitoring of symptoms during preoperative chemoradiotherapy, particularly at week 4, will enable the implementation of timely interventions so that interruptions to treatment are prevented and the quality of life is optimised, which may hasten postoperative recovery times.
Assuntos
Qualidade de Vida , Neoplasias Retais/psicologia , Idoso , Idoso de 80 Anos ou mais , Quimiorradioterapia Adjuvante , Constipação Intestinal/etiologia , Fadiga/etiologia , Feminino , Humanos , Irlanda , Masculino , Pessoa de Meia-Idade , Náusea/etiologia , Medição da Dor , Período Pré-Operatório , Estudos Prospectivos , Neoplasias Retais/complicações , Neoplasias Retais/enfermagem , Neoplasias Retais/terapia , Inquéritos e Questionários , Vômito/etiologiaRESUMO
The biologically and clinically important membrane transporters are challenging proteins to study because of their low level of expression, multidomain structure, and complex molecular dynamics that underlies their activity. ATP7B is a copper transporter that traffics between the intracellular compartments in response to copper elevation. The N-terminal domain of ATP7B (N-ATP7B) is involved in binding copper, but the role of this domain in trafficking is controversial. To clarify the role of N-ATP7B, we generated nanobodies that interact with ATP7B in vitro and in cells. In solution NMR studies, nanobodies revealed the spatial organization of N-ATP7B by detecting transient functionally relevant interactions between metal-binding domains 1-3. Modulation of these interactions by nanobodies in cells enhanced relocalization of the endogenous ATP7B toward the plasma membrane linking molecular and cellular dynamics of the transporter. Stimulation of ATP7B trafficking by nanobodies in the absence of elevated copper provides direct evidence for the important role of N-ATP7B structural dynamics in regulation of ATP7B localization in a cell.
Assuntos
Adenosina Trifosfatases/metabolismo , Proteínas de Transporte de Cátions/metabolismo , Cobre/metabolismo , Anticorpos de Domínio Único/metabolismo , Adenosina Trifosfatases/química , Adenosina Trifosfatases/genética , Sequência de Aminoácidos , Animais , Sítios de Ligação/genética , Western Blotting , Camelídeos Americanos , Proteínas de Transporte de Cátions/química , Proteínas de Transporte de Cátions/genética , Membrana Celular/metabolismo , Cobre/química , ATPases Transportadoras de Cobre , Células HEK293 , Humanos , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Espectroscopia de Ressonância Magnética , Microscopia Confocal , Modelos Moleculares , Dados de Sequência Molecular , Ligação Proteica , Estrutura Terciária de Proteína , Transporte Proteico , Homologia de Sequência de Aminoácidos , Anticorpos de Domínio Único/química , Anticorpos de Domínio Único/genéticaRESUMO
Due to the growing need to provide alternatives to fossil fuels as efficiently, economically, and sustainably as possible there has been growing interest in improved biofuel production systems. Biofuels produced from microalgae are a particularly attractive option since microalgae have production potentials that exceed the best terrestrial crops by 2 to 10-fold. In addition, autotrophically grown microalgae can capture CO2 from point sources reducing direct atmospheric greenhouse gas emissions. The enhanced biomass production potential of algae is attributed in part to the fact that every cell is photosynthetic. Regardless, overall biological energy capture, conversion, and storage in microalgae are inefficient with less than 8% conversion of solar into chemical energy achieved. In this review, we examine the thermodynamic and kinetic constraints associated with the autotrophic conversion of inorganic carbon into storage carbohydrate and oil, the dominant energy storage products in Chlorophytic microalgae. We discuss how thermodynamic restrictions including the loss of fixed carbon during acetyl CoA synthesis reduce the efficiency of carbon accumulation in lipids. In addition, kinetic limitations, such as the coupling of proton to electron transfer during plastoquinone reduction and oxidation and the slow rates of CO2 fixation by Rubisco reduce photosynthetic efficiency. In some cases, these kinetic limitations have been overcome by massive increases in the numbers of effective catalytic sites, e.g. the high Rubisco levels (mM) in chloroplasts. But in other cases, including the slow rate of plastoquinol oxidation, there has been no compensatory increase in the abundance of catalytically limiting protein complexes. Significantly, we show that the energetic requirements for producing oil and starch relative to the recoverable energy stored in these molecules are very similar on a per carbon basis. Presently, the overall rates of starch and lipid synthesis in microalgae are very poorly characterized. Increased understanding of the kinetic constraints of lipid and starch synthesis, accumulation and turnover would facilitate the design of improved biomass production systems.
RESUMO
Cells use the redox properties of copper in numerous physiologic processes, including antioxidant defense, neurotransmitter biosynthesis, and angiogenesis. Copper delivery to the secretory pathway is an essential step in copper utilization and homeostatic maintenance. We demonstrate that the glutathione/glutathione disulfide (GSH/GSSG) pair controls the copper transport pathway by regulating the redox state of a copper chaperone Atox1. GSSG oxidizes copper-coordinating cysteines of Atox1 with the formation of an intramolecular disulfide. GSH alone is sufficient to reduce the disulfide, restoring the ability of Atox1 to bind copper; glutaredoxin 1 facilitates this reaction when GSH is low. In cells, high GSH both reduces Atox1 and is required for cell viability in the absence of Atox1. In turn, Atox1, which has a redox potential similar to that of glutaredoxin, becomes essential for cell survival when GSH levels decrease. Atox1(+/+) cells resist short term glutathione depletion, whereas Atox1(-/-) cells under the same conditions are not viable. We conclude that GSH balance and copper homeostasis are functionally linked and jointly maintain conditions for copper secretion and cell proliferation.
Assuntos
Proteínas de Transporte de Cátions/fisiologia , Cobre/metabolismo , Glutationa/metabolismo , Chaperonas Moleculares/fisiologia , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/fisiologia , Sequência de Aminoácidos , Transporte Biológico , Proteínas de Transporte de Cátions/química , Proteínas de Transporte de Cátions/genética , Linhagem Celular , Proteínas de Transporte de Cobre , ATPases Transportadoras de Cobre , Glutationa Redutase/metabolismo , Humanos , Metalochaperonas , Chaperonas Moleculares/química , OxirreduçãoRESUMO
Copper transfer to cuproproteins located in vesicular compartments of the secretory pathway depends on activity of the copper-translocating ATPase (ATP7A), but the mechanism of transfer is largely unexplored. Copper-ATPase ATP7A is unique in having a sequence rich in histidine and methionine residues located on the lumenal side of the membrane. The corresponding fragment binds Cu(I) when expressed as a chimera with a scaffold protein, and mutations or deletions of His and/or Met residues in its sequence inhibit dephosphorylation of the ATPase, a catalytic step associated with copper release. Here we present evidence for a potential role of this lumenal region of ATP7A in copper transfer to cuproenzymes. Both Cu(II) and Cu(I) forms were investigated since the form in which copper is transferred to acceptor proteins is currently unknown. Analysis of Cu(II) using EPR demonstrated that at Cu:P ratios below 1:1 (15)N-substituted protein had Cu(II) bound by 4 His residues, but this coordination changed as the Cu(II) to protein ratio increased toward 2:1. XAS confirmed this coordination via analysis of the intensity of outer-shell scattering from imidazole residues. The Cu(II) complexes could be reduced to their Cu(I) counterparts by ascorbate, but here again, as shown by EXAFS and XANES spectroscopy, the coordination was dependent on copper loading. At low copper Cu(I) was bound by a mixed ligand set of His + Met, whereas at higher ratios His coordination predominated. The copper-loaded loop was able to transfer either Cu(II) or Cu(I) to peptidylglycine monooxygenase in the presence of chelating resin, generating catalytically active enzyme in a process that appeared to involve direct interaction between the two partners. The variation of coordination with copper loading suggests copper-dependent conformational change which in turn could act as a signal for regulating copper release by the ATPase pump.
Assuntos
Adenosina Trifosfatases/química , Proteínas de Transporte de Cátions/química , Oxigenases de Função Mista/metabolismo , Complexos Multienzimáticos/metabolismo , Adenosina Trifosfatases/genética , Sequência de Aminoácidos , Animais , Domínio Catalítico , Proteínas de Transporte de Cátions/genética , Cobre/química , ATPases Transportadoras de Cobre , Humanos , Camundongos , Oxigenases de Função Mista/química , Oxigenases de Função Mista/genética , Modelos Moleculares , Dados de Sequência Molecular , Complexos Multienzimáticos/química , Complexos Multienzimáticos/genética , Ligação Proteica , Alinhamento de Sequência , Espectroscopia por Absorção de Raios XRESUMO
The copper-transporting ATPase ATP7A has an essential role in human physiology. ATP7A transfers the copper cofactor to metalloenzymes within the secretory pathway; inactivation of ATP7A results in an untreatable neurodegenerative disorder, Menkes disease. Presently, the mechanism of ATP7A-mediated copper release into the secretory pathway is not understood. We demonstrate that the characteristic His/Met-rich segment Met(672)-Pro(707) (HM-loop) that connects the first two transmembrane segments of ATP7A is important for copper release. Mutations within this loop do not prevent the ability of ATP7A to form a phosphorylated intermediate during ATP hydrolysis but inhibit subsequent dephosphorylation, a step associated with copper release. The HM-loop inserted into a scaffold protein forms two structurally distinct binding sites and coordinates copper in a mixed His-Met environment with an â¼2:1 stoichiometry. Binding of either copper or silver, a Cu(I) analog, induces structural changes in the loop. Mutations of 4 Met residues to Ile or two His-His pairs to Ala-Gly decrease affinity for copper. Altogether, the data suggest a two-step process, where copper released from the transport sites binds to the first His(Met)(2) site, triggering a structural change and binding to a second 2-coordinate His-His or His-Met site. We also show that copper binding within the HM-loop stabilizes Cu(I) and protects it from oxidation, which may further aid the transfer of copper from ATP7A to acceptor proteins. The mechanism of copper entry into the secretory pathway is discussed.
Assuntos
Adenosina Trifosfatases/metabolismo , Proteínas de Transporte de Cátions/metabolismo , Cobre/metabolismo , Adenosina Trifosfatases/química , Adenosina Trifosfatases/genética , Trifosfato de Adenosina/química , Trifosfato de Adenosina/genética , Trifosfato de Adenosina/metabolismo , Sítios de Ligação , Transporte Biológico/genética , Proteínas de Transporte de Cátions/química , Proteínas de Transporte de Cátions/genética , Linhagem Celular , Cobre/química , ATPases Transportadoras de Cobre , Humanos , Síndrome dos Cabelos Torcidos/genética , Síndrome dos Cabelos Torcidos/metabolismo , Mutação , Ligação Proteica , Estrutura Secundária de Proteína , Prata/química , Prata/metabolismoRESUMO
Copper-transporting ATPase ATP7B is essential for human copper homeostasis and normal liver function. ATP7B has six N-terminal metal-binding domains (MBDs) that sense cytosolic copper levels and regulate ATP7B. The mechanism of copper sensing and signal integration from multiple MBDs is poorly understood. We show that MBDs communicate and that this communication determines the oxidation state and conformation of the entire N-terminal domain of ATP7B (N-ATP7B). Mutations of copper-coordinating Cys to Ala in any MBD (2, 3, 4, or 6) change the N-ATP7B conformation and have distinct functional consequences. Mutating MBD2 or MBD3 causes Cys oxidation in other MBDs and loss of copper binding. In contrast, mutation of MBD4 and MBD6 does not alter the redox status and function of other sites. Our results suggest that MBD2 and MBD3 work together to regulate access to other metal-binding sites, whereas MBD4 and MBD6 receive copper independently, downstream of MBD2 and MBD3. Unlike Ala substitutions, the Cys-to-Ser mutation in MBD2 preserves the conformation and reduced state of N-ATP7B, suggesting that hydrogen bonds contribute to interdomain communications. Tight coupling between MBDs suggests a mechanism by which small changes in individual sites (induced by copper binding or mutation) result in stabilization of distinct conformations of the entire N-ATP7B and altered exposure of sites for interactions with regulatory proteins.