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1.
J Am Med Dir Assoc ; 24(2): 134-139, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36592942

RESUMO

The COVID-19 pandemic had a big impact on assisted living (AL), a vital setting in long-term care (LTC). Understanding the strengths and opportunities for improvement through practice, policy, and research are essential for AL to be prepared for the next pandemic and other challenges. AL communities experienced the pandemic in unique ways, because of varying regulatory environments, differences in familiarity with using and procuring personal protective equipment not typically used in AL (such as N95 masks), loss of family involvement, the homelike environment, and lower levels of licensed clinical staff. Being state rather than federally regulated, much less national data are available about the COVID-19 experience in AL. This article reviews what is known about cases and deaths, infection control, and the impact on residents and staff. For each, we suggest actions that could be taken and link them to the Assisted Living Workgroup Report (ALW) recommendations. Using the Center for Excellence in Assisted Living (CEAL) 15-year ALW report, we also review which of these recommendations have and have not been implemented by states in the preceding decade and half, and how their presence or absence may have affected AL pandemic preparedness. Finally, we provide suggestions for policy, practice, and research moving forward, including improving state-level reporting, staff vaccine requirements, staff training and work-life, levels of research-provider partnerships, dissemination of research, and uptake of a holistic model of care for AL.


Assuntos
COVID-19 , Humanos , Assistência de Longa Duração , Pandemias/prevenção & controle , Controle de Infecções
2.
JAMA Netw Open ; 5(9): e2233872, 2022 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-36173637

RESUMO

Importance: Assisted living (AL) is the largest provider of residential long-term care in the US, and the morbidity of AL residents has been rising. However, AL is not a health care setting, and concern has been growing about residents' medical and mental health needs. No guidance exists to inform this care. Objective: To identify consensus recommendations for medical and mental health care in AL and determine whether they are pragmatic. Evidence Review: A Delphi consensus statement study was conducted in 2021; as a separate effort, the extent to which the recommendations are reflected in practice was examined in data obtained from 2016 to 2021 (prepandemic). In the separate effort, data were from a 7-state study (Arkansas, Louisiana, New Jersey, New York, Oklahoma, Pennsylvania, Texas). The 19 Delphi panelists constituted nationally recognized experts in medical, nursing, and mental health needs of and care for older adults; dementia care; and AL and long-term care management, advocacy, regulation, and education. One invitee was unavailable and nominated an alternate. The primary outcome was identification of recommended practices based on consensus ratings of importance. Panelists rated 183 items regarding importance to care quality and feasibility. Findings: Consensus identified 43 recommendations in the areas of staff and staff training, nursing and related services, resident assessment and care planning, policies and practices, and medical and mental health clinicians and care. To determine the pragmatism of the recommendations, their prevalence was examined in the 7-state study and found that most were in practice. The items reflected the tenets of AL, the role of AL in providing dementia care, the need for pragmatism due to the diversity of AL, and workforce needs. Conclusions and Relevance: In this consensus statement, 43 recommendations important to medical and mental health care in AL were delineated that are highly pragmatic as a guide for practice and policy.


Assuntos
Consenso , Demência , Idoso , Técnica Delphi , Demência/terapia , Humanos , Estados Unidos
3.
Geriatr Nurs ; 44: 282-287, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35219533

RESUMO

Randomized controlled trials are considered the most rigorous research design in efficacy and effectiveness research; however, such trials present numerous challenges that limit their applicability in real-world settings. As a consequence, pragmatic trials are increasingly viewed as a research design that overcomes some of these barriers with the potential to produce data that are more reproducible. Although pragmatic methodology in long-term care is receiving increasing attention as an approach to improve successful dissemination and implementation, pragmatic trials present complexities of their own. To address these complexities and related issues, experts with experience conducting pragmatic trials, developing nursing home policy, participating in advocacy efforts, and providing clinical care in long-term care settings participated in a virtual consensus conference funded by the National Institute on Aging in Spring 2021. Participants recommended 4 cross-cutting principles key to dissemination and implementation of pragmatic trial interventions: (1) engage stakeholders, (2) ensure diversity and inclusion, (3) assess organizational strain and readiness, and (4) learn from adaptations. Specifically related to implementation, participants provided 2 recommendations: (1) integrate interventions into existing workflows and (2) maintain agility and responsiveness. Finally, participants had 3 recommendations specific to dissemination: (1) package the message for the audience, (2) engage diverse audiences, and (3) apply dissemination and diffusion tools. Participants emphasized that implementation processes must be grounded in the perspectives of the people who will ultimately be responsible for implementing the intervention once it is proven to be effective. In addition, messaging must speak to long-term care staff and all others who have a stake in its outcomes. Although our understanding of dissemination and implementation strategies remains underdeveloped, this article is designed to guide long-term care researchers and community providers who are increasingly aware of the need for pragmatism in disseminating and implementing evidence-based care interventions.


Assuntos
Assistência de Longa Duração , Ensaios Clínicos Pragmáticos como Assunto , Humanos , Casas de Saúde
4.
J Am Geriatr Soc ; 70(3): 709-717, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35195281

RESUMO

Randomized controlled trials are considered the most rigorous research design in efficacy and effectiveness research; however, such trials present numerous challenges that limit their applicability in real-world settings. As a consequence, pragmatic trials are increasingly viewed as a research design that overcomes some of these barriers with the potential to produce findings that are more reproducible. Although pragmatic methodology in long-term care is receiving increasing attention as an approach to improve successful dissemination and implementation, pragmatic trials present complexities of their own. To address these complexities and related issues, experts with experience conducting pragmatic trials, developing nursing home policy, participating in advocacy efforts, and providing clinical care in long-term care settings participated in a virtual consensus conference funded by the National Institute on Aging in Spring 2021. Participants identified 4 cross-cutting principles key to dissemination and implementation of pragmatic trial interventions: (1) stakeholder engagement, (2) diversity and inclusion, (3) organizational strain and readiness, and (4) learn from adaptations. Participants emphasized that implementation processes must be grounded in the perspectives of the people who will ultimately be responsible for implementing the intervention once it is proven to be effective. In addition, messaging must speak to long-term care staff and all others who have a stake in its outcomes. Although our understanding of dissemination and implementation strategies remains underdeveloped, this article is designed to guide long-term care researchers and community providers who are increasingly aware of the need for pragmatism in disseminating and implementing evidence-based care interventions.


Assuntos
Casas de Saúde , Ensaios Clínicos Pragmáticos como Assunto , Humanos , Assistência de Longa Duração , Participação dos Interessados
5.
J Am Med Dir Assoc ; 23(2): 225-234, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34979136

RESUMO

Assisted living (AL) has existed in the United States for decades, evolving in response to older adults' need for supportive care and distaste for nursing homes and older models of congregate care. AL is state-regulated, provides at least 2 meals a day, around-the-clock supervision, and help with personal care, but is not licensed as a nursing home. The key constructs of AL as originally conceived were to provide person-centered care and promote quality of life through supportive and responsive services to meet scheduled and unscheduled needs for assistance, an operating philosophy emphasizing resident choice, and a residential environment with homelike features. As AL has expanded to constitute half of all long-term care beds, the increasing involvement of the real estate, hospitality, and health care sectors has raised concerns about the variability of AL, the quality of AL, and standards for AL. Although the intent to promote person-centered care and quality of life has remained, those key constructs have become mired under tensions related to models of AL, regulation, financing, resident acuity, and the workforce. These tensions have resulted in a model of care that is not as intended, and which must be reimagined if it is to be an affordable care option truly providing quality, person-centered care in a suitable environment. Toward that end, 25 stakeholders representing diverse perspectives conferred during 2 half-day retreats to identify the key tensions in AL and discuss potential solutions. This article presents the background regarding those tensions, as well as potential solutions that have been borne out, paving the path to a better future of assisted living.


Assuntos
Casas de Saúde , Qualidade de Vida , Idoso , Humanos , Assistência de Longa Duração , Instituições de Cuidados Especializados de Enfermagem , Estados Unidos
6.
J Am Med Dir Assoc ; 23(3): 339-344, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34919838

RESUMO

Randomized controlled trials are considered the most rigorous research design in efficacy and effectiveness research; however, such trials present numerous challenges that limit their applicability in real-world settings. As a consequence, pragmatic trials are increasingly viewed as a research design that overcomes some of these barriers with the potential to produce findings that are more reproducible. Although pragmatic methodology in long-term care is receiving increasing attention as an approach to improve successful dissemination and implementation, pragmatic trials present complexities of their own. To address these complexities and related issues, experts with experience conducting pragmatic trials, developing nursing home policy, participating in advocacy efforts, and providing clinical care in long-term care settings participated in a virtual consensus conference funded by the National Institute on Aging in Spring 2021. Participants identified 4 cross-cutting principles key to dissemination and implementation of pragmatic trial interventions: (1) stakeholder engagement, (2) diversity and inclusion, (3) organizational strain and readiness, and (4) learn from adaptations. Participants emphasized that implementation processes must be grounded in the perspectives of the people who will ultimately be responsible for implementing the intervention once it is proven to be effective. In addition, messaging must speak to long-term care staff and all others who have a stake in its outcomes. Although our understanding of dissemination and implementation strategies remains underdeveloped, this article is designed to guide long-term care researchers and community providers who are increasingly aware of the need for pragmatism in disseminating and implementing evidence-based care interventions.


Assuntos
Assistência de Longa Duração , Casas de Saúde , Humanos , Participação dos Interessados
7.
J Exp Biol ; 224(Pt 4)2021 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-33526554

RESUMO

Food-induced morphological plasticity, a type of developmental plasticity, is a well-documented phenomenon in larvae of the echinoid echinoderm, Dendraster excentricus A recent study in our lab has shown that this morphological plasticity is associated with significant physiological plasticity for growth. The goal of the current study was to measure several aspects of protein metabolism in larvae growing at different rates to understand the mechanistic basis for this physiological growth plasticity. Larvae of D. excentricus were fed rations of 1000 algal cells ml-1 (low-fed larvae) or 10,000 algal cells ml-1 (high-fed larvae). Relative protein growth rate was 6.0 and 12.2% day-1 for low- and high-fed larvae, respectively. The energetic cost of protein synthesis was similar for the two treatments at 4.91 J mg-1 protein synthesized. Larvae in both treatments used about 50% of their metabolic energy production to fuel protein synthesis. Mass-specific rates of protein synthesis were also similar. Large differences in mass-specific rates of protein degradation were observed. Low-fed larvae had relatively low rates of degradation early in development that increased with larval age, surpassing those of high-fed larvae at 20 days post-fertilization. Changes in protein depositional efficiency during development were similar to those of larval growth efficiency, indicating that differences in protein metabolism are largely responsible for whole-organism growth plasticity. Low-fed larvae also had alanine transport rates that were 2 times higher than those of high-fed larvae. In total, these results provide an explanation for the differences in growth efficiency between low- and high-fed larvae and allow for a more integrated understanding of developmental plasticity in echinoid larvae.


Assuntos
Alimentos , Proteínas , Animais , Larva , Morfogênese , Biossíntese de Proteínas
8.
J Am Med Dir Assoc ; 21(11): 1582-1586.e1, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32723533

RESUMO

In April, 2019, the Alzheimer's Association Dementia Care Provider Roundtable convened to discuss common challenges faced when implementing person-centered, non-pharmacological practices in long-term care and other settings that provide care and programs for persons living with dementia, and to develop relevant, specific guidance from the perspective of administrative leaders from 23 long-term and community-based care provider organizations (representing home, community-based, and residential care). Guidance related to 5 practice areas emerged from the facilitated discussion: having a foundational person-centered culture, conceptualizing behaviors as expressions and focusing on behavioral support, identifying antecedents and placing person-centeredness before protocols, modifying training to promote person-centered culture, and valuing implementation flexibility. In developing the practice guidance, a related list of priority areas for research and policy were also identified.


Assuntos
Doença de Alzheimer , Demência , Doença de Alzheimer/terapia , Demência/terapia , Humanos , Assistência de Longa Duração , Assistência Centrada no Paciente , Autocuidado
9.
Methods Cell Biol ; 150: 105-123, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30777173

RESUMO

Although sea urchins are one of the oldest and most widely used marine model systems, few species have been routinely kept in culture through multiple generations. The workhorse of the field is the purple urchin Strongylocentrotus purpuratus. However, one disadvantage of S. purpuratus is its long generation time, making it impractical as a model for generating and maintaining transgenic lines. In an effort to develop a sea urchin that is suitable for transgenerational experiments and the generation of transgenic lines, we have focused on development of updated culturing methods and genomic resources for the painted sea urchin, Lytechinus pictus. Compared to S. purpuratus, L. pictus have relatively large eggs, develop into optically clear embryos, and the smaller adults can become gravid in under a year. Fifty years ago, Hinegardner developed culturing methods for raising L. pictus through metamorphosis. Here, we provide an updated protocol for establishing and maintaining L. pictus in the laboratory, and describe a new genome resource for this urchin. In our hands, L. pictus reach the 4-armed pluteus stage at 4 days; become competent to metamorphosis at 24 days; and are gravid by 6 months. Plutei and juveniles are fed on a diet of algae and diatoms, and adults are fed on kelp. We also make available a L. pictus transcriptome generated from developmental stages (eggs to 2-day-old plutei) to support the annotation of our genome sequencing project, and to enhance the utility of this species for molecular studies and transgenesis.


Assuntos
Lytechinus/citologia , Lytechinus/genética , Ouriços-do-Mar/citologia , Ouriços-do-Mar/genética , Animais , Animais Geneticamente Modificados/genética , Embrião não Mamífero/citologia , Genoma/genética , Modelos Animais , Transcriptoma/genética , Sequenciamento Completo do Genoma/métodos
10.
Gerontologist ; 58(suppl_1): S10-S19, 2018 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-29361064

RESUMO

Background and Objectives: Person-centered care is a philosophy of care built around the needs of the individual and contingent upon knowing the unique individual through an interpersonal relationship. This review article outlines the history, components, and impact of person-centered care practices. Research Design and Methods: Through literature review, published articles on person-centered measures and outcomes were examined. Results: The history of person-centered care was described, core principles of care for individuals with dementia outlined, current tools to measure person-centered care approaches reviewed, and outcomes of interventions discussed. Discussion and Implications: Evidence-based practice recommendations for person-centered care for individuals with dementia are outlined. More research is needed to further assess the outcomes of person-centered care approaches and models.


Assuntos
Demência/terapia , Prática Clínica Baseada em Evidências/métodos , Assistência Centrada no Paciente/organização & administração , Humanos , Avaliação de Resultados em Cuidados de Saúde
12.
J Biol Chem ; 290(45): 26914-26926, 2015 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-26374900

RESUMO

Toxoplasma gondii is an obligate intracellular parasite that invades host cells, creating a parasitophorous vacuole where it communicates with the host cell cytosol through the parasitophorous vacuole membrane. The lytic cycle of the parasite starts with its exit from the host cell followed by gliding motility, conoid extrusion, attachment, and invasion of another host cell. Here, we report that Ca(2+) oscillations occur in the cytosol of the parasite during egress, gliding, and invasion, which are critical steps of the lytic cycle. Extracellular Ca(2+) enhances each one of these processes. We used tachyzoite clonal lines expressing genetically encoded calcium indicators combined with host cells expressing transiently expressed calcium indicators of different colors, and we measured Ca(2+) changes in both parasites and host simultaneously during egress. We demonstrated a link between cytosolic Ca(2+) oscillations in the host and in the parasite. Our approach also allowed us to measure two new features of motile parasites, which were enhanced by Ca(2+) influx. This is the first study showing, in real time, Ca(2+) signals preceding egress and their direct link with motility, an essential virulence trait.


Assuntos
Sinalização do Cálcio , Toxoplasma/fisiologia , Animais , Ionóforos de Cálcio/farmacologia , Sinalização do Cálcio/efeitos dos fármacos , Sinalização do Cálcio/genética , Linhagem Celular , Células HeLa , Interações Hospedeiro-Parasita/genética , Interações Hospedeiro-Parasita/fisiologia , Humanos , Ionomicina/farmacologia , Proteínas Luminescentes/genética , Proteínas Recombinantes/genética , Toxoplasma/genética , Toxoplasma/patogenicidade , Transfecção , Virulência
13.
Mol Microbiol ; 93(4): 698-712, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24975633

RESUMO

The vacuolar proton pyrophosphatase (H(+) -PPase) of Toxoplasma gondii (TgVP1), a membrane proton pump, localizes to acidocalcisomes and a novel lysosome-like compartment termed plant-like vacuole (PLV) or vacuolar compartment (VAC). We report the characterization of a T. gondii null mutant for the TgVP1 gene. Propagation of these mutants decreased significantly because of deficient attachment and invasion of host cells, which correlated with deficient microneme secretion. Processing of cathepsin L (CPL) in these mutants was deficient only when the parasites were incubated in the presence of low concentrations of the vacuolar H(+) -ATPase (V-H(+) -ATPase) inhibitor bafilomycin A1 , suggesting that either TgVP1 or the T. gondii V-H(+) -ATPase (TgVATPase) are sufficient to support CPL processing. The lack of TgVP1 did not affect processing of micronemal proteins, indicating that it does not contribute to proMIC maturations. The TgVP1 null mutants were more sensitive to extracellular conditions and were less virulent in mice. We demonstrate that T. gondii tachyzoites possess regulatory volume decrease capability during hypo-osmotic stress and this ability is impaired in TgVP1 null mutants implicating TgVP1 in osmoregulation. We hypothesize that osmoregulation is needed for host cell invasion and that TgVP1 plays a role during the normal lytic cycle of T. gondii.


Assuntos
Moléculas de Adesão Celular/metabolismo , Sobrevivência Celular , Endocitose , Pirofosfatase Inorgânica/metabolismo , Toxoplasma/enzimologia , Vacúolos/enzimologia , Animais , Modelos Animais de Doenças , Deleção de Genes , Pirofosfatase Inorgânica/genética , Camundongos , Toxoplasma/metabolismo , Toxoplasma/fisiologia , Toxoplasmose Animal , Vacúolos/metabolismo , Virulência
14.
J Biol Chem ; 289(28): 19637-47, 2014 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-24867952

RESUMO

During invasion and egress from their host cells, Apicomplexan parasites face sharp changes in the surrounding calcium ion (Ca(2+)) concentration. Our work with Toxoplasma gondii provides evidence for Ca(2+) influx from the extracellular milieu leading to cytosolic Ca(2+) increase and enhancement of virulence traits, such as gliding motility, conoid extrusion, microneme secretion, and host cell invasion. Assays of Mn(2+) and Ba(2+) uptake do not support a canonical store-regulated Ca(2+) entry mechanism. Ca(2+) entry was blocked by the L-type Ca(2+) channel inhibitor nifedipine and stimulated by the increase in cytosolic Ca(2+) and by the specific L-type Ca(2+) channel agonist Bay K-8644. Our results demonstrate that Ca(2+) entry is critical for parasite virulence. We propose a regulated Ca(2+) entry mechanism activated by cytosolic Ca(2+) that has an enhancing effect on invasion-linked traits.


Assuntos
Canais de Cálcio Tipo L/metabolismo , Cálcio/metabolismo , Proteínas de Protozoários/metabolismo , Locos de Características Quantitativas/fisiologia , Toxoplasma/metabolismo , Toxoplasma/patogenicidade , Éster Metílico do Ácido 3-Piridinacarboxílico, 1,4-Di-Hidro-2,6-Dimetil-5-Nitro-4-(2-(Trifluormetil)fenil)/farmacologia , Animais , Bário/metabolismo , Agonistas dos Canais de Cálcio/farmacologia , Humanos , Manganês/metabolismo , Proteínas de Protozoários/antagonistas & inibidores , Toxoplasmose/metabolismo
15.
Essays Biochem ; 51: 97-110, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22023444

RESUMO

Calcium is relevant for several vital functions in apicomplexan parasites, including host cell invasion, parasite motility and differentiation. The ER (endoplasmic reticulum) and calcium-rich acidocalcisomes have been identified as major calcium stores. Other potential calcium-storage organelles include the Golgi, the mitochondrion, the apicoplast and the recently described plant-like vacuole in Toxoplasma gondii. Compared with most eukaryotic systems, apicomplexan parasites contain a reduced number of calcium-related genes, a vast majority of which remain uncharacterized. Several Ca²âº-ATPases have been described in apicomplexans, several of which are annotated in the different genomes. There is experimental evidence for an IP3 (inositol 1,4,5-trisphosphate)-dependent calcium response in Plasmodium spp. and T. gondii, although no IP3 or ryanodine receptors have been identified. Genes encoding potential calcium channels are present in T. gondi, but not in Plasmodium spp. and Cryptosporidium spp. Effector calcium-binding proteins including calmodulins and CDPK (calcium-dependent protein kinase) genes mainly found in plants have also been described. The characterized CDPKs were found to play important roles in protein secretion, host cell invasion and parasite differentiation. Taken together, the available information on calcium storage and function in apicomplexans, although fragmented, suggest the existence of unique calcium-mediated pathways in these parasites. An in-depth functional characterization of the apicomplexan calcium-related genes could lead to the identification of novel therapeutic targets, and will improve our understanding of the role of calcium in parasite development and virulence.


Assuntos
Apicomplexa/metabolismo , Cálcio/metabolismo , Animais , Apicomplexa/genética , Apicomplexa/patogenicidade , Canais de Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ligação ao Cálcio/metabolismo , ATPases Transportadoras de Cálcio/genética , ATPases Transportadoras de Cálcio/metabolismo , Retículo Endoplasmático/metabolismo , Inositol 1,4,5-Trifosfato/metabolismo , Mitocôndrias/metabolismo , Proteínas Quinases/metabolismo , Infecções por Protozoários/metabolismo , Infecções por Protozoários/parasitologia
16.
Biochem J ; 440(2): 229-40, 2011 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-21831041

RESUMO

PP(i) is a critical element of cellular metabolism as both an energy donor and as an allosteric regulator of several metabolic pathways. The apicomplexan parasite Toxoplasma gondii uses PP(i) in place of ATP as an energy donor in at least two reactions: the glycolytic PP(i)-dependent PFK (phosphofructokinase) and V-H(+)-PPase [vacuolar H(+)-translocating PPase (pyrophosphatase)]. In the present study, we report the cloning, expression and characterization of cytosolic TgPPase (T. gondii soluble PPase). Amino acid sequence alignment and phylogenetic analysis indicates that the gene encodes a family I soluble PPase. Overexpression of the enzyme in extracellular tachyzoites led to a 6-fold decrease in the cytosolic concentration of PP(i) relative to wild-type strain RH tachyzoites. Unexpectedly, this subsequent reduction in PP(i) was associated with a higher glycolytic flux in the overexpressing mutants, as evidenced by higher rates of proton and lactate extrusion. In addition to elevated glycolytic flux, TgPPase-overexpressing tachyzoites also possessed higher ATP concentrations relative to wild-type RH parasites. These results implicate PP(i) as having a significant regulatory role in glycolysis and, potentially, other downstream processes that regulate growth and cell division.


Assuntos
Difosfatos/metabolismo , Glicólise/fisiologia , Pirofosfatase Inorgânica/biossíntese , Fosfotransferases/metabolismo , Toxoplasma/enzimologia , Sequência de Aminoácidos , Sequência de Bases , Citosol/enzimologia , Dados de Sequência Molecular , Organelas/metabolismo , Toxoplasma/genética
17.
Exp Cell Res ; 317(10): 1382-96, 2011 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-21501607

RESUMO

The obligate intracellular parasite Toxoplasma gondii is exposed to a variety of physiological conditions while propagating in an infected organism. The mechanisms by which Toxoplasma overcomes these dramatic changes in its environment are not known. In yeast and plants, ion detoxification and osmotic regulation are controlled by vacuolar compartments. A novel compartment named the plant-like vacuole or vacuolar compartment (PLV/VAC) has recently been described in T.gondii, which could potentially protect extracellular tachyzoites against salt and other ionic stresses. Here, we report the molecular characterization of the vacuolar type Na(+)/H(+) exchanger in T. gondii, TgNHE3, and its co-localization with the PLV/VAC proton-pyrophosphatase (TgVP1). We have created a TgNHE3 knockout strain, which is more sensitive to hyperosmotic shock and toxic levels of sodium, possesses a higher intracellular Ca(2+) concentration [Ca(2+)](i), and exhibits a reduced host invasion efficiency. The defect in invasion correlates with a measurable reduction in the secretion of the adhesin TgMIC2. Overall, our results suggest that the PLV/VAC has functions analogous to those of the vacuolar compartments of plants and yeasts, providing the parasite with a mechanism to resist ionic fluctuations and, potentially, regulate protein trafficking.


Assuntos
Movimento Celular , Proteínas de Protozoários/metabolismo , Trocadores de Sódio-Hidrogênio/metabolismo , Toxoplasma/metabolismo , Vacúolos/metabolismo , Equilíbrio Hidroeletrolítico/fisiologia , Sequência de Aminoácidos , Animais , Apoptose , Western Blotting , Cálcio/metabolismo , Adesão Celular , Proliferação de Células , Clonagem Molecular , Fibroblastos , Imunofluorescência , Cobaias , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Transporte Proteico , Prótons , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Pirofosfatases/genética , Pirofosfatases/metabolismo , Homologia de Sequência de Aminoácidos , Trocadores de Sódio-Hidrogênio/genética , Trocadores de Sódio-Hidrogênio/imunologia , Toxoplasma/genética , Toxoplasma/crescimento & desenvolvimento , Toxoplasmose
18.
Biochem J ; 429(3): 485-95, 2010 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-20497125

RESUMO

Acidocalcisomes are acidic calcium-storage compartments described from bacteria to humans and characterized by their high content in poly P (polyphosphate), a linear polymer of many tens to hundreds of Pi residues linked by high-energy phosphoanhydride bonds. In the present paper we report that millimolar levels of short-chain poly P (in terms of Pi residues) and inorganic PPi are present in sea urchin extracts as detected using 31P-NMR, enzymatic determinations and agarose gel electrophoresis. Poly P was localized to granules randomly distributed in the sea urchin eggs, as shown by labelling with the poly-P-binding domain of Escherichia coli exopolyphosphatase. These granules were enriched using iodixanol centrifugation and shown to be acidic and to contain poly P, as determined by Acridine Orange and DAPI (4',6'-diamidino-2-phenylindole) staining respectively. These granules also contained large amounts of calcium, sodium, magnesium, potassium and zinc, as detected by X-ray microanalysis, and bafilomycin A1-sensitive ATPase, pyrophosphatase and exopolyphosphatase activities, as well as Ca2+/H+ and Na+/H+ exchange activities, being therefore similar to acidocalcisomes described in other organisms. Calcium release from these granules induced by nigericin was associated with poly P hydrolysis. Although NAADP (nicotinic acid-adenine dinucleotide phosphate) released calcium from the granule fraction, this activity was not significantly enriched as compared with the NAADP-stimulated calcium release from homogenates and was not accompanied by poly P hydrolysis. GPN (glycyl-L-phenylalanine-naphthylamide) released calcium when added to sea urchin homogenates, but was unable to release calcium from acidocalcisome-enriched fractions, suggesting that these acidic stores are not the targets for NAADP.


Assuntos
Cálcio/metabolismo , Grânulos Citoplasmáticos/metabolismo , NADP/análogos & derivados , Óvulo/metabolismo , Polifosfatos/metabolismo , Ácidos/metabolismo , Animais , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , NADP/metabolismo , Óvulo/ultraestrutura , Ouriços-do-Mar
19.
Mol Microbiol ; 76(6): 1358-75, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20398214

RESUMO

Toxoplasma gondii belongs to the phylum Apicomplexa and is an important cause of congenital disease and infection in immunocompromised patients. Like most apicomplexans, T. gondii possesses several plant-like features, such as the chloroplast-like organelle, the apicoplast. We describe and characterize a novel organelle in T. gondii tachyzoites, which is visible by light microscopy and possesses a broad similarity to the plant vacuole. Electron tomography shows the interaction of this vacuole with other organelles. The presence of a plant-like vacuolar proton pyrophosphatase (TgVP1), a vacuolar proton ATPase, a cathepsin L-like protease (TgCPL), an aquaporin (TgAQP1), as well as Ca(2+)/H(+) and Na(+)/H(+) exchange activities, supports similarity to the plant vacuole. Biochemical characterization of TgVP1 in enriched fractions shows a functional similarity to the respective plant enzyme. The organelle is a Ca(2+) store and appears to have protective effects against salt stress potentially linked to its sodium transport activity. In intracellular parasites, the organelle fragments, with some markers colocalizing with the late endosomal marker, Rab7, suggesting its involvement with the endocytic pathway. Studies on the characterization of this novel organelle will be relevant to the identification of novel targets for chemotherapy against T. gondii and other apicomplexan parasites as well.


Assuntos
Toxoplasma/fisiologia , Toxoplasma/ultraestrutura , Vacúolos/metabolismo , Vacúolos/ultraestrutura , Antiporters/metabolismo , Cálcio/metabolismo , Tomografia com Microscopia Eletrônica , Endocitose , Microscopia , Pressão Osmótica , Plantas/ultraestrutura , Bombas de Próton/metabolismo , Proteínas de Protozoários/análise , Sódio/metabolismo , Estresse Fisiológico , Vacúolos/química , Vacúolos/enzimologia
20.
Biol Bull ; 218(1): 48-60, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20203253

RESUMO

Previous research has shown that developing stages of the Antarctic sea urchin Sterechinus neumayeri have high rates of protein synthesis that are comparable to those of similar species living in much warmer waters. Direct measurements of the biosynthetic capacities of isolated ribosomes have not been reported for marine organisms living in the extreme-cold environment of Antarctica. Such measurements are required for a mechanistic understanding of how the critical and highly complex processes involved in protein synthesis are regulated in animals living in the coldest marine environment on Earth (< -1 degrees C). We tested the hypothesis that high rates of protein synthesis in the cold are a direct result of high biosynthetic capacities of ribosomes engaged in protein synthesis. Our results show that the rate at which ribosomes manufacture proteins (i.e., the peptide elongation rate) at -1 degrees C is surprisingly similar to rates measured in other sea urchin species at temperatures that are over 15 degrees C warmer. Average peptide elongation rates for a range of developmental stages of the Antarctic sea urchin were 0.36 codons s(-1) (+/- 0.05, SE). On the basis of subcellular rate determinations of ribosomal activity, we calculated stage-specific rates of protein synthesis for blastulae and gastrulae to be 3.7 and 6.5 ng protein h(-1), respectively. These findings support the conclusion that the high rates of biosynthesis previously reported for the Antarctic sea urchin are an outcome of high ribosomal activities.


Assuntos
Biossíntese de Proteínas , Ribossomos/metabolismo , Ouriços-do-Mar/metabolismo , Animais , Regiões Árticas , Ouriços-do-Mar/crescimento & desenvolvimento
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