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The birth of a premature infant and its subsequent hospitalization in the neonatal intensive care unit are stressful experiences for mothers. Because of uncertainty concerning interactions with a premature baby, mothers often feel helpless and only hesitantly assume their maternal role. This may have a negative impact on the mother-child interaction and prevents mothers from taking an active part in E46www.jpnnjournal.com the care for their child. "Creating Opportunities for Parent Empowerment" (COPE) is a 4-phase educational intervention program aiming to systematically involve parents into caring for their premature infant. In this pretest-posttest quasi-experimental study in 2 Swiss university hospitals, we focused on maternal self-efficacy. We compared self-efficacy in mothers receiving the COPE program or standard care alone at baseline and 3 months after estimated delivery date. To measure maternal self-efficacy, we used the "Tool to measure Parenting Self-Efficacy" (TOPSE). While scores for "Emotion and Affection," "Empathy and Understanding," as well as "Learning and Knowledge" increased in both groups, only "Learning and Knowledge" scores were significantly higher in the intervention group. Given the intention of improving learning and knowledge, the COPE program might be a promising intervention contributing to enhanced maternal self-efficacy.
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Recém-Nascido Prematuro , Relações Mãe-Filho , Mães , Autoeficácia , Humanos , Feminino , Recém-Nascido , Mães/psicologia , Mães/educação , Adulto , Adaptação Psicológica , Unidades de Terapia Intensiva Neonatal/organização & administração , Suíça , Poder Familiar/psicologiaRESUMO
OBJECTIVE: The objective is to identify risk factors that potentially prolong the hospital stay in patients after undergoing first single-level open lumbar microdiscectomy. METHODS: A retrospective single-centre study was conducted. Demographic data, medical records, intraoperative course, and imaging studies were analysed. The outcome measure was defined by the number of days stayed after the operation. A prolonged length of stay (LOS) stay was defined as a minimum of one additional day beyond the median hospital stay in our patient collective. Bivariate analysis and multiple stepwise regression were used to identify independent factors related to the prolonged hospital stay. RESULTS: Two hundred consecutive patients who underwent first lumbar microdiscectomy between 2018 and 2022 at our clinic were included in this study. Statistical analysis of factors potentially prolonging postoperative hospital stay was done for a total of 24 factors, seven of them were significantly related to prolonged LOS in bivariate analysis. Sex (p = 0.002, median 5 vs. 4 days for females vs. males) and age (rs = 0.35, p ≤ 0.001, N = 200) were identified among the examined demographic factors. Regarding preoperative physical status, preoperative immobility reached statistical significance (p ≤ 0.001, median 5 vs. 4 days). Diabetes mellitus (p = 0.043, median 5 vs. 4 days), anticoagulation and/or antiplatelet agents (p = 0.045, median 5 vs. 4 days), and postoperative narcotic consumption (p ≤ 0.001, median 5 vs. 4 days) as comorbidities were associated with a prolonged hospital stay. Performance of nucleotomy (p = 0.023, median 5 vs. 4 days) was a significant intraoperative factor. After linear stepwise multivariable regression, only preoperative immobility (p ≤ 0.001) was identified as independent risk factors for prolonged length of postoperative hospital stay. CONCLUSION: Our study identified preoperative immobility as a significant predictor of prolonged hospital stay, highlighting its value in preoperative assessments and as a tool to pinpoint at-risk patients. Prospective clinical trials with detailed assessment of mobility, including grading, need to be done to verify our results.
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Discotomia , Feminino , Masculino , Humanos , Tempo de Internação , Estudos Prospectivos , Estudos Retrospectivos , Fatores de RiscoRESUMO
Multifunctional nanoparticles are discussed as versatile probes for homogeneous immunoassays for in-vitro diagnostics. Top-down fabrication allows to combine and tailor magnetic and plasmonic anisotropic properties. The combination of nanoimprint lithography, thin film deposition, and lift-off processing provides a top-down fabrication platform, which is both flexible and reliable. Here, we discuss the material compositions and geometrical designs of monodisperse multicomponent nanoparticles and their consequences on optical and magnetic properties. The rotational hydrodynamics of nanoparticles is measured and considered under the influence of magnetic shape anisotropy in the framework of the Stoner-Wohlfarth theory. The plasmon-optical properties are explained by discrete-dipole finite-element simulations. Rotational dynamical measurements of imprinted nanoprobes for two test proteins demonstrate the applicability as highly sensitive biomolecular nanoprobes.
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BACKGROUND: Family-centered care interventions are a recommended part of high-quality neonatal intensive care. Evidence suggests that engaging and supporting families improves parental and infant health outcomes. Enabling practitioners to work with families in a relational, strength-oriented way is thus vital to ensure quality care. However, implementing family-centered care remains a challenge, and its uptake is often slow and inconsistent. OBJECTIVES: To examine the impact of family systems care implementation activities on neonatal nurses' and physicians' attitudes and skills in working with families, and to explore their implementation experience. DESIGN: Mixed method design. SETTING AND PARTICIPANTS: Two neonatal intensive and one intermediate care unit in a Swiss, university-affiliated hospital. A total of 65 practitioners participated in the pre-post study, and 17 in focus group interviews. METHODS: Quantitative data was obtained before, mid-, and post-implementation through an online questionnaire. Attitudes were measured with the Families' Importance in Nursing Care - Nurses' Attitudes Scale. Skills and reciprocity in working with families was assessed with the Family Nursing Practice Scale. Four focus group interviews were conducted post-implementation. Data analysis included descriptive statistics, group comparison, and qualitative content analysis. RESULTS: A statistically significant increase in practice skills and reciprocity, but not in attitudes was found mid- and post-implementation. Practitioners reported new ways of working with families, which included enhanced awareness of the extended family, intentional relationship-building, augmented family involvement, and systemic interventions, such as therapeutic listening. They experienced implementation as a wheel that moved forward or stood still, depending on the challenges faced and the predominance of enabling versus limiting organizational factors. Practitioners felt not only challenged regarding the meaning of being-acting in family-centered ways, but also in delivering family systems care consistently and collaboratively. While practitioners experienced the educational workshop as helpful, they felt left alone during consolidation. CONCLUSIONS: Findings demonstrate that the inter-professional implementation of family systems care is highly relevant for practitioners' clinical practice. Implementation strategies yielded an increase in practice skills/reciprocity and new ways of working with families, but no quantifiable impact on attitudes. Adoption fluctuated and was ongoing, hindered by organizational constraints and lack of consolidation support. Nonetheless, practitioners gave numerous examples of family-centered practices. A combination of implementation strategies offered over time and supported by organizational structures are the most likely means to enable teams to work in partnership with families, and to promote infant and family well-being in neonatal care.
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Atitude do Pessoal de Saúde , Competência Clínica , Família , Corpo Clínico Hospitalar/psicologia , Neonatologia , Recursos Humanos de Enfermagem Hospitalar/psicologia , Adulto , Feminino , Humanos , Recém-Nascido , Masculino , Qualidade da Assistência à SaúdeRESUMO
Nanostructured surfaces and nanoparticles are already widely employed in many different fields of research, and there is an ever-growing demand for reliable, reproducible and scalable nanofabrication methods. This is especially valid for multifunctional nanomaterials with physical properties that are tailored for specific applications. Here, we report on the fabrication of two types of nanomaterials. Specifically, we present surfaces comprising a highly uniform array of elliptical pillars as well as nanoparticles with the shape of nanopockets, possessing nano-cavities. The structures are fabricated by nanoimprint lithography, physical and wet-chemical etching and sputter deposition of thin films of various materials to achieve a multifunctional nanomaterial with defined optical and magnetic properties. We show that the nanopockets can be transferred to solution, yielding a nanoparticle dispersion. All fabrication steps are carefully characterized by microscopic and optical methods. Additionally, we show optical simulation results that are in good agreement with the experimentally obtained data. Thus, this versatile method allows to fabricate nanomaterials with specific tailor-made physical properties that can be designed by modelling prior to the actual fabrication process. Finally, we discuss possible application areas of these nanomaterials, which range from biology and medicine to electronics, photovoltaics and photocatalysis.
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Pediatric heart transplant recipients are scarce and widely dispersed. Previous studies of adolescents in this population were limited to small homogenous samples. Although online focus groups are an emerging data collection method, its use in pediatric populations has not been fully realized. The purpose of this study was to explore the feasibility of using online focus groups with pediatric populations. Adolescents (aged 13 to 21 years) at least 6 months post-heart transplant and their parents were recruited from two children's hospitals. An online discussion forum (iTracks) was used to conduct asynchronous focus groups with separate parent and adolescent groups. Six parents and four adolescents participated in the discussions. iTracks provided a framework for conducting focus groups in dispersed populations. Access to the discussion transcripts enhanced data analysis and eliminated transcription costs. Overall, online discussion forums were a feasible and cost-effective option to conduct online focus groups in this pediatric population.
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Transplante de Coração , Adolescente , Adulto , Grupos Focais , Humanos , Projetos PilotoRESUMO
The "raspberry task" represents a precision grip task that requires continuous adjustment of grip forces and pull forces. During this task, subjects use a specialised grip rod and have to increase the pull force linearly while the rod is locked. The positions of the fingers are unrestrained and freely selectable. From the finger positions and the geometry of the grip rod, a physical lever was derived which is a comprehensive measurement of the subject's grip behaviour. In this study, the involvement of the cerebellum in establishing cued force changes (CFC) was examined. The auditory stimulus was associated with a motor behaviour that has to be readjusted during an ongoing movement that already started. Moreover, cerebellar involvement on grip behaviour was examined. The results show that patients presenting with degenerating cerebellar disease (CBL) were able to elicit CFC and were additionally able to optimise grip behaviour by minimising the lever. Comparison of the results of CBL with a control group of healthy subjects showed, however, that the CFC incidence was significantly lower and the reduction of the lever was less in CBL. Hence, the cerebellum is involved not only in the classical conditioning of reflexes but also in the association of sensory stimuli with complex changes in motor behaviour. Furthermore, the cerebellum is involved in the optimisation of grip behaviour during ongoing movements. Recent studies lead to the assumption that the cerebello-reticulo-spinal pathway might be important for the reduced optimisation of grip behaviour in CBL.
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Cerebelo/fisiopatologia , Sinais (Psicologia) , Força da Mão/fisiologia , Contração Isométrica/fisiologia , Destreza Motora/fisiologia , Degenerações Espinocerebelares/fisiopatologia , Estimulação Acústica , Adaptação Psicológica/fisiologia , Adulto , Idoso , Percepção Auditiva/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Degenerações Espinocerebelares/psicologiaRESUMO
A quality improvement project for implementing safe sleep practices (SSP) was conducted at a large, U.S children's hospital. The intervention involved education of staff and standardization of infant sleep practices utilizing a multifaceted approach. Staff surveys and environmental audits were conducted pre- and post-intervention. Safe Sleep Environment (SSE) audits showed an improvement from 23% to 34% (p<0.001) post-intervention. Staff confidence to provide education to caregivers on SSP showed a significant increase. Results from this project demonstrate a successful approach to implement SSP in the hospital setting. Infant safe sleep practices have the potential to reduce infant mortality.
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Melhoria de Qualidade/organização & administração , Gestão da Segurança/organização & administração , Sono/fisiologia , Morte Súbita do Lactente/prevenção & controle , Comitês Consultivos , Feminino , Guias como Assunto , Hospitais Pediátricos , Humanos , Lactente , Cuidado do Lactente/organização & administração , Mortalidade Infantil/tendências , Recém-Nascido , Masculino , Segurança do Paciente , Avaliação de Programas e Projetos de Saúde , Decúbito Dorsal , Centros de Atenção Terciária , Estados UnidosRESUMO
The "raspberry task" represents a precision grip task that requires continuous adjustment of grip and pull forces. During this task subjects grip a specialized grip rod and have to increase the pull force linearly while the rod is locked. The aim of this study was to determine whether an associated, initially neutral cue is able to evoke pull-force changes in the raspberry task. A standard delay paradigm was used to study cued pull-force changes during an ongoing movement resulting in unloading. Pull force and EMG activity of hand and arm muscles were recorded from 13 healthy, young subjects. The cue was associated with a complex change in motor behavior. In this task, cued force changes take place more rapidly than in protective reflex systems (in median after the second presentation of the cueing stimulus). A cued force change was detectable in two-thirds of paired trials. Although the force change is produced by a decrease of the EMG activity in several grip- and pull-force-producing muscles, the most significant effect in the majority of the subjects was an increase of the activity of the flexor carpi ulnaris muscle which antagonises corresponding pull-force-producing muscles. Cued force changes require adequately and precisely controlled activation of the muscle groups involved in the movement.
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Eletromiografia/métodos , Força da Mão/fisiologia , Contração Isométrica/fisiologia , Aprendizagem , Adulto , Sinais (Psicologia) , Feminino , Dedos/fisiologia , Humanos , Masculino , Destreza Motora , Movimento , Músculo Esquelético/fisiologia , Estresse Mecânico , Adulto JovemRESUMO
CONTEXT: Little is known about adolescent transition to self-management after heart transplant. This gap in knowledge is critically important because the consequences of poor self-management are costly and life-threatening, often resulting in nonadherence, rejection, repeated hospitalizations, and poor quality of life. OBJECTIVE: To explore how adolescents and parents perceive their roles in self-management, and how adolescents integrate self-management into their daily lives and navigate the transition from parent-dominated to self-management. DESIGN: Qualitative descriptive design, using online focus groups. SETTING: Online focus groups using itracks, an online qualitative software program. PARTICIPANTS: A purposive sample of 4 adolescents, 13 to 21 years old, who were at least 6 months posttransplant, and of 6 parents of adolescent heart transplant recipients. RESULTS: Several parallel themes emerged from the parent and adolescent online focus groups. Managing medications was the predominant theme for both parents and adolescents. For the remaining themes, parents and adolescents expressed similar ideas that were categorized into parallel themes, which included staying on top of things/becoming independent, letting them be normal/being normal, and worries and stressors. CONCLUSIONS: The transition to self-management after heart transplant was a clear goal for both parents and adolescents. The transition is a shared responsibility between parents and adolescents with a gradual shift from parent-directed to self-management. The process of transition was not linear or smooth, and in several instances, parents described efforts to transfer responsibility to the adolescent only to take it back when complications arose. Additional research with a larger sample is needed in order to fully understand adolescent heart transplant recipients' transition to self-management.
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Transplante de Coração/psicologia , Psicologia do Adolescente , Autocuidado/métodos , Autocuidado/psicologia , Atividades Cotidianas/psicologia , Adaptação Psicológica , Adolescente , Feminino , Grupos Focais , Objetivos , Humanos , Internet , Masculino , Relações Pais-Filho , Pesquisa Qualitativa , Qualidade de Vida , Adulto JovemRESUMO
Although mentoring is an important aspect of implementing evidence-based practice (EBP), few models exist for EBP education. The EBP Academy is an innovative, 6-month educational program designed to develop clinical staff as EBP nurse mentors. Sessions provide protected time for participants to work on their EBP projects with assigned mentors who have EBP expertise and similar clinical or research interests. Participants develop EBP projects focused on improving care in their clinical areas. Evaluation of the EBP Academy is based on a four-level model, including participant feedback about the program, perception of meeting program objectives, ability to apply knowledge to practice through EBP projects, and outcome data measured as a result of implementing the EBP changes. By developing EBP mentors, capacity to move nursing practice to a stronger evidence-based foundation can be enhanced. Positive, professional nursing and patient outcomes have been demonstrated when structured EBP education is provided.
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Educação Continuada em Enfermagem/métodos , Prática Clínica Baseada em Evidências/educação , Mentores/educação , Recursos Humanos de Enfermagem Hospitalar/educação , Terapia Respiratória/educação , Humanos , Modelos Educacionais , Pesquisa em Avaliação de Enfermagem , Desenvolvimento de ProgramasRESUMO
This study addresses the influence of the cerebellum on the performance of an isometric precision grip task. For the task, in which the process of "picking a raspberry" is simulated, grip force and pull force had to be increased linearly for a duration of 1-5 s (pull phase) to accomplish the task skillfully. The performance of 11 patients suffering from degenerative cerebellar disease was analyzed and compared with the performance of 11 age- and sex-matched healthy control subjects. Patients with cerebellar disease showed systematic deviations of the pull force slope from a linear trend, dividing the pull phase into two intervals. After an initial sharp and brief increase of pull force (first interval), patients maintained the achieved pull force level almost constant without further increase (second interval). Although controls showed changes in the pull force slope also, they increased pull force during the whole pull phase. Coupling of grip force and pull force was analyzed using stochastic frontier analysis. This technique allows covariation of grip force and the resulting pull force to be analyzed depending on the variation of the grip force. In the patients, grip force and pull force were coupled efficiently only in the first interval. During the second interval, grip force was often exaggerated compared with pull force. In conclusion, patients with cerebellar diseases have difficulties in producing smooth isometric movements and in coupling grip force and pull force efficiently.
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Doenças Cerebelares/fisiopatologia , Cerebelo/fisiologia , Força da Mão/fisiologia , Contração Isométrica/fisiologia , Destreza Motora/fisiologia , Força Muscular/fisiologia , Adulto , Idoso , Estudos de Casos e Controles , Doenças Cerebelares/diagnóstico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de TempoRESUMO
BACKGROUND: The aim of this case report was to describe the clinical findings, treatment and outcome of lumbosacral discospondylitis in a calf. CASE PRESENTATION: A 5.5-month-old calf was presented with difficulty in rising, a stiff and slightly ataxic gait in the hind limbs and a shortened stride. The lumbosacral region was severely painful on palpation.Radiographic examination confirmed lumbosacral discospondylitis. Medical treatment with stall rest was instituted over six weeks. Radiographic and ultrasonographic follow-up examinations showed lysis of the endplates initially, then collapse of the intervertebral space at the lumbosacral junction and progressive sclerosis in the periphery of the lytic zones. Four weeks after institution of treatment, the calf could rise normally and the general condition gradually had returned to normal. The calf was discharged after 6 weeks and was sound at 3.5 months clinical and radiographic follow up examination. Thereafter, it was kept on alpine pastures without problems and was pregnant 1 year after the last examination. CONCLUSIONS: This report shows that recovery from lumbosacral discospondylitis is possible in heifers, provided that treatment is started before major neurologic deficits have developed and is continued for an extended period of time.
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Anti-Infecciosos/uso terapêutico , Doenças dos Bovinos/diagnóstico , Cefalosporinas/uso terapêutico , Discite/veterinária , Animais , Bovinos , Doenças dos Bovinos/diagnóstico por imagem , Doenças dos Bovinos/tratamento farmacológico , Discite/diagnóstico , Discite/diagnóstico por imagem , Discite/tratamento farmacológico , Feminino , Região Lombossacral/diagnóstico por imagem , Radiografia , UltrassonografiaRESUMO
Safe and effective cell delivery remains one of the main challenges in cell-based therapy of neurodegenerative disorders. Graft survival, sufficient enrichment of therapeutic cells in the brain, and avoidance of their distribution throughout the peripheral organs are greatly influenced by the method of delivery. Here we demonstrate for the first time noninvasive intranasal (IN) delivery of mesenchymal stem cells (MSCs) to the brains of unilaterally 6-hydroxydopamine (6-OHDA)-lesioned rats. IN application (INA) of MSCs resulted in the appearance of cells in the olfactory bulb, cortex, hippocampus, striatum, cerebellum, brainstem, and spinal cord. Out of 1 × 106 MSCs applied intranasally, 24% survived for at least 4.5 months in the brains of 6-OHDA rats as assessed by quantification of enhanced green fluorescent protein (EGFP) DNA. Quantification of proliferating cell nuclear antigen-positive EGFP-MSCs showed that 3% of applied MSCs were proliferative 4.5 months after application. INA of MSCs increased the tyrosine hydroxylase level in the lesioned ipsilateral striatum and substantia nigra, and completely eliminated the 6-OHDA-induced increase in terminal deoxynucleotidyl transferase (TdT)-mediated 2'-deoxyuridine, 5'-triphosphate (dUTP)-biotin nick end labeling (TUNEL) staining of these areas. INA of EGFP-labeled MSCs prevented any decrease in the dopamine level in the lesioned hemisphere, whereas the lesioned side of the control animals revealed significantly lower levels of dopamine 4.5 months after 6-OHDA treatment. Behavioral analyses revealed significant and substantial improvement of motor function of the Parkinsonian forepaw to up to 68% of the normal value 40-110 days after INA of 1 × 106 cells. MSC-INA decreased the concentrations of inflammatory cytokines-interleukin-1ß (IL-1ß), IL-2, -6, -12, tumor necrosis factor (TNF), interferon-γ (IFN-γ, and granulocyte-macrophage colony-stimulating factor (GM-CSF)-in the lesioned side to their levels in the intact hemisphere. IN administration provides a highly promising noninvasive alternative to the traumatic surgical procedure of transplantation and allows targeted delivery of cells to the brain with the option of chronic application.
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Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Doença de Parkinson/terapia , Administração Intranasal , Animais , Western Blotting , Proliferação de Células , Modelos Animais de Doenças , Células HEK293 , Células HeLa , Humanos , Interleucinas/metabolismo , Masculino , Neostriado/enzimologia , Neostriado/patologia , Oxidopamina , Ratos , Ratos Sprague-Dawley , Substância Negra/enzimologia , Substância Negra/patologia , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
UNLABELLED: The skin of preterm infants is anatomically and physiologically premature. This quality of the skin as well as the need for intensive monitoring and treatment/care represent additional stress factors for the integrity of the babies' skin. The babies have an increased vulnerability and risk of skin injuries. Therefore, during the first two to three weeks of life observation of the premature skin is of utmost importance. Ritualistic activities have to be questioned. This is particularly true for infants who are born before 28 weeks of pregnancy. This systematic literature review investigates the effectiveness of nursing interventions in the skin care and protection of the premature infants born earlier than the 32nd week of pregnancy. A systematic literature-search in different databases addressed the following topics: Skin-assessment, selection and use of adhesives, skin care with emollients, and body cleaning (wash interval). Despite certain methodological problems with some of the studies included in this review the following results can be formulated: Based on altered infant behaviour and the skin's continuously high population of germs the interval of bathing should be enhanced to four days. During the first two to four weeks of life the application of sun flower oil is recommended. It has a disinfecting effect and is relatively cheap. Potential preventive or protective dressings of the skin are recommended. Similarly both the utilisation of a valid skin assessment instrument and of preventive measures are inevitable. CONCLUSION: Evidence-based knowledge of the needs and care of premature skin could reduce complications during the neonatal phase and therefore health care costs. The implementation of a standardised, evidence-based skin care guideline could raise the health professionals' awareness in of skin care needs in this vulnerable patient group.
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Ictiose/enfermagem , Doenças do Prematuro/enfermagem , Higiene da Pele/enfermagem , Dermatopatias/enfermagem , Bandagens , Banhos , Idade Gestacional , Humanos , Recém-Nascido , Recém-Nascido de muito Baixo Peso , Óleos de Plantas/administração & dosagem , Óleo de GirassolRESUMO
Sweet potato plants were grown with or without Glomus intraradices in split-root pots with adjacent root compartments containing a soil with a low availability of phosphate. One fungal tube, from which root growth was excluded, was inserted into each root compartment. During 4 weeks before harvest, the soil moisture level in either both or only one of the two root-compartments of each pot was decreased. Controls remained well watered. Low soil moisture generally had a negative effect on the amount of extraradical mycelium of G. intraradices extracted from the fungal tubes. Sporulation in the fungal tubes was much higher compared with the soil in the root compartment, but remained unaffected by the soil moisture regime. Concentrations of P in extraradical mycelium were much lower than usually found in plants and fungi, while P concentrations in associated mycorrhizal host plant tissues were in an optimum range. This suggests efficient transfer of P from the extraradical mycelium to the host plant. Despite the negative effect of a low soil moisture regime on extraradical G. intraradices development, the symbiosis indeed contributed significantly to P uptake of plants exposed to partial rootzone drying. The possibility that extraradical arbuscular mycorrhizal fungal development was limited by P availability under dry soil conditions is discussed.
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Glomeromycota , Ipomoea batatas/crescimento & desenvolvimento , Micélio/crescimento & desenvolvimento , Micorrizas , Raízes de Plantas , Simbiose , Secas , Glomeromycota/crescimento & desenvolvimento , Glomeromycota/metabolismo , Ipomoea batatas/microbiologia , Micorrizas/crescimento & desenvolvimento , Micorrizas/metabolismo , Fosfatos/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Solo/análise , Água/análiseRESUMO
Listeria monocytogenes are important foodborne pathogens that can cause outbreaks of serious human disease. These organisms frequently colonize and proliferate on preserved food products despite exposure to stress conditions induced by low storage temperatures, inclusion of organic acid-based preservatives, and high osmolarity. To assess alternative sigma factor sigma(L) contributions to such stress resistance of L. monocytogenes, quantitative RT-PCR assays and sigL gene deletion mutagenesis were applied in L. monocytogenes EGDe. Transcription of sigL was significantly induced by growth of EGDe under cold, organic acid, and elevated NaCl salt concentration stress conditions. The growth of a DeltasigL strain exposed to these stress conditions was also found to be significantly impaired in comparison to that of its isogenic wild-type strain. The contribution of sigma(L) to transcription control of cold and NaCl stress adaptation genes, oppA, cspD, and clpP, was also comparatively assessed in DeltasigL and wild-type EGDe cells. Transcription of the oppA gene, which encodes the OppA protein that also promotes L. monocytogenes cold growth, was significantly reduced in cold stress-grown DeltasigL cells compared to levels of the wild-type EGDe strain. These findings therefore suggest important roles of sigma(L) regulatory pathways in facilitating resistance of L. monocytogenes organisms against stress conditions associated with low storage temperatures, exposure to organic acid, and elevated NaCl salt concentrations.
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Microbiologia de Alimentos , Listeria monocytogenes/crescimento & desenvolvimento , Fator sigma/fisiologia , Adaptação Biológica , Temperatura Baixa , DNA Bacteriano/genética , Meio Ambiente , Deleção de Genes , Expressão Gênica , Ácido Láctico/administração & dosagem , Listeria monocytogenes/genética , Mutagênese , Concentração Osmolar , Fator sigma/genética , Cloreto de Sódio/administração & dosagemRESUMO
The gram-positive bacterium Listeria monocytogenes is a food-borne pathogen of both public health and food safety significance. It possesses three small, highly homologous protein members of the cold shock protein (Csp) family. We used gene expression analysis and a set of mutants with single, double, and triple deletions of the csp genes to evaluate the roles of CspA, CspB, and CspD in the cold and osmotic (NaCl) stress adaptation responses of L. monocytogenes. All three Csps are dispensable for growth at optimal temperature (37 degrees C). These proteins are, however, required for efficient cold and osmotic stress tolerance of this bacterium. The hierarchies of their functional importance differ, depending on the environmental stress conditions: CspA>CspD>CspB in response to cold stress versus CspD>CspA/CspB in response to NaCl salt osmotic stress. The fact that Csps are promoting L. monocytogenes adaptation against both cold and NaCl stress has significant implications in view of practical food microbial control measures. The combined or sequential exposure of L. monocytogenes cells to these two stresses in food environments might inadvertently induce cross-protection responses.