276 research outputs found
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Cryopreservation of winter-dormant apple: III Bud water status and survival after cooling to -30°c and during recovery from cryopreservation
Abstract
In a continuing study to improve the efficiency of dormant bud cryopreservation for
tissues hardened in maritime climates, the water status of dormant buds was monitored
between -4°C and recovery from liquid nitrogen (LN). Measurement of water content, simple
thermal analysis and differential scanning calorimetry were employed. Buds did not lose
water during cooling to, or holding at -30°C indicating that cryodehydration and/or other
adaptive responses contributed during this essential step. A bud exotherm that was an artefact
of warming was detected due to necessary handling at -4°C before cooling to -30°C. There
were no significant differences between cultivars with respect to water status at -30°C or
immediately upon rewarming from LN despite significant differences in post-LN survival.
Buds rehydrated in 5 days, but up to 14 days may be needed for recovery for some cultivars.
In some instances buds could be grafted without rehydration, taking up water across the early
graft union
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Cryopreservation of winter-dormant apple buds: II - tissue water status after desiccation at -4°c and before further cooling
Abstract
The established protocol for the cryopreservation of winter-dormant Malus buds requires
that stem explants, containing a single, dormant bud are desiccated at -4°C, for up to 14 days,
to reduce their water content to 25-30% of fresh weight. Using three apple cultivars, with
known differences in response to cryopreservation, the pattern of evaporative water loss has
been characterised, including early freezing events in the bud and cortical tissues that allow
further desiccation by water migration to extracellular ice. There were no significant
differences between cultivars in this respect or in the proportions of tissue water lost during
the desiccation process. Differential Scanning Calorimetry (to -90°C) of intact buds indicated
that bud tissues of the cultivar with the poorest response to cryopreservation had the highest
residual water content at the end of the desiccation process and froze at the highest
temperature
Keywords: Malus, cryopreservation, dormant bud, dehydratio
Appropriate use criteria for transesophageal echocardiography in Greece: A single center experience
Introduction The American College of Cardiology Foundation (ACCF) along with the American Society of Echocardiography (ASE) have enabled an accurate and clinically oriented evaluation of echocardiography indications by introducing Appropriate Use Criteria (AUC). Aim This study was designed to evaluate the degree of implementation of AUC for transesophageal echocardiography (TEE) during daily clinical practice in a tertiary university hospital in Greece during the era of economic recession. Materials and Methods From November 2014 to May 2014, we prospectively enrolled 300 patients who were examined in the Echocardiography Laboratory of the First University Cardiology. We recorded the participants' demographic and clinical characteristics using questionnaires and followed a scoring process according to ACCF guidelines to classify patients into an appropriate, inappropriate or uncertain category. The primary endpoint was to assess the association between the class of appropriateness and abnormal TEE results. Results In 89.4% of patients labelled appropriate, TEE was abnormal and significantly higher compared to patients of uncertain eligibility (50%) and to patients for whom TEE was considered to be inappropriate (35%) (p < 0.001). Subgroup analysis revealed a positive association between AUC and an increased possibility for abnormal TEE in female subjects (p = 0.001) as well as in patients who were younger than 50 years old (p < 0.001). A significant association was finally established between AUC and abnormal findings in TEE in patients with no risk factors (p = 0.028) and in patients with more than 3 risk factors (p = 0.013). Conclusion TEE constitutes a medical practice with an optimal cost/effectiveness ratio and should be further encouraged in our country in accordance with the austerity policy as long as the AUC are generally applied
Did Clinical Trials in Which Erythropoietin Failed to Reduce Acute Myocardial Infarct Size Miss a Narrow Therapeutic Window?
Background: To test a hypothesis that in negative clinical trials of erythropoietin in patients with acute myocardial infarction (MI) the erythropoietin (rhEPO) could be administered outside narrow therapeutic window. Despite overwhelming evidence of cardioprotective properties of rhEPO in animal studies, the outcomes of recently concluded phase II clinical trials have failed to demonstrate the efficacy of rhEPO in patients with acute MI. However, the time between symptoms onset and rhEPO administration in negative clinical trials was much longer that in successful animal experiments. Methodology/Principal Findings: MI was induced in rats either by a permanent ligation of a descending coronary artery or by a 2-hr occlusion followed by a reperfusion. rhEPO, 3000 IU/kg, was administered intraperitoneally at the time of reperfusion, 4 hrs after beginning of reperfusion, or 6 hrs after permanent occlusion. MI size was measured histologically 24 hrs after coronary occlusion. The area of myocardium at risk was similar among groups. The MI size in untreated rats averaged,42 % of area at risk, or,24 % of left ventricle, and was reduced by more than 50 % (p,0.001) in rats treated with rhEPO at the time of reperfusion. The MI size was not affected by treatment administered 4 hrs after reperfusion or 6 hrs after permanent coronary occlusion. Therefore, our study in a rat experimental model of MI demonstrates that rhEPO administered within 2 hrs of a coronary occlusion effectively reduces MI size, but when rhEPO was administered following a delay similar to that encountered in clinical trials, it had no effect on MI size
Crosstalk between JNK and SUMO Signaling Pathways: deSUMOylation Is Protective against H2O2-Induced Cell Injury
Background: Oxidative stress is a key feature in the pathogenesis of several neurological disorders. Following oxidative stress stimuli a wide range of pathways are activated and contribute to cellular death. The mechanism that couples c-Jun N-terminal kinase (JNK) signaling, a key pathway in stress conditions, to the small ubiquitin-related modifier (SUMO), an emerging protein in the field, is largely unknown. Methodology/Principal Findings: With this study we investigated if SUMOylation participates in the regulation of JNK activation as well as cellular death in a model of H 2O 2 induced-oxidative stress. Our data show that H 2O 2 modulates JNK activation and induces cellular death in neuroblastoma SH-SY5Y cells. Inhibition of JNK’s action with the D-JNKI1 peptide rescued cells from death. Following H2O2, SUMO-1 over-expression increased phosphorylation of JNK and exacerbated cell death, although only in conditions of mild oxidative stress. Furthermore inhibition of SUMOylation, following transfection with SENP1, interfered with JNK activation and rescued cells from H 2O 2 induced death. Importantly, in our model, direct interaction between these proteins can occur. Conclusions/Significance: Taken together our results show that SUMOylation may significantly contribute to modulation o
Targeted inhibition of mitochondrial Hsp90 suppresses localised and metastatic prostate cancer growth in a genetic mouse model of disease
BACKGROUND: The molecular chaperone heat shock protein-90 (Hsp90) is a promising cancer drug target, but current Hsp90-based therapy has so far shown limited activity in the clinic.
METHODS: We tested the efficacy of a novel mitochondrial-targeted, small-molecule Hsp90 inhibitor, Gamitrinib (GA mitochondrial matrix inhibitor), in the Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP) model. The TRAMP mice receiving 3-week or 5-week systemic treatment with Gamitrinib were evaluated for localised or metastatic prostate cancer, prostatic intraepithelial neoplasia (PIN) or localised inflammation using magnetic resonance imaging, histology and immunohistochemistry. Treatment safety was assessed histologically in organs collected at the end of treatment. The effect of Gamitrinib on mitochondrial dysfunction was studied in RM1 cells isolated from TRAMP tumours.
RESULTS: Systemic administration of Gamitrinib to TRAMP mice inhibited the formation of localised prostate tumours of neuroendocrine or adenocarcinoma origin, as well as metastatic prostate cancer to abdominal lymph nodes and liver. The Gamitrinib treatment had no effect on PIN or prostatic inflammation, and caused no significant animal weight loss or organ toxicity. Mechanistically, Gamitrinib triggered acute mitochondrial dysfunction in RM1 cells, with loss of organelle inner membrane potential and release of cytochrome-c in the cytosol.
CONCLUSIONS: The Gamitrinib has pre-clinical activity and favourable tolerability in a genetic model of localised and metastatic prostate cancer in immunocompetent mice. Selective targeting of mitochondrial Hsp90 could provide novel molecular therapy for patients with advanced prostate cancer
Establishment of a Novel Fluorescence-Based Method to Evaluate Chaperone-Mediated Autophagy in a Single Neuron
Background: Chaperone-mediated autophagy (CMA) is a selective autophagy-lysosome protein degradation pathway. The role of CMA in normal neuronal functions and in neural disease pathogenesis remains unclear, in part because there is no available method to monitor CMA activity at the single-cell level. Methodology/Principal Findings: We sought to establish a single-cell monitoring method by visualizing translocation of CMA substrates from the cytosol to lysosomes using the HaloTag (HT) system. GAPDH, a CMA substrate, was fused to HT (GAPDH-HT); this protein accumulated in the lysosomes of HeLa cells and cultured cerebellar Purkinje cells (PCs) after labeling with fluorescent dye-conjugated HT ligand. Lysosomal accumulation was enhanced by treatments that activate CMA and prevented by siRNA-mediated knockdown of LAMP2A, a lysosomal receptor for CMA, and by treatments that inactivate CMA. These results suggest that lysosomal accumulation of GAPDH-HT reflects CMA activity. Using this method, we revealed that mutant cPKC, which causes spinocerebellar ataxia type 14, decreased CMA activity in cultured PCs. Conclusion/Significance: In the present study, we established a novel fluorescent-based method to evaluate CMA activity in a single neuron. This novel method should be useful and valuable for evaluating the role of CMA in various neurona
Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome
Study QuestionWhat is the recommended assessment and management of women with polycystic ovary syndrome (PCOS), based on the best available evidence, clinical expertise, and consumer preference? Summary AnswerInternational evidence-based guidelines including 166 recommendations and practice points, addressed prioritized questions to promote consistent, evidence-based care and improve the experience and health outcomes of women with PCOS. What is Known AlreadyPrevious guidelines either lacked rigorous evidence-based processes, did not engage consumer and international multidisciplinary perspectives, or were outdated. Diagnosis of PCOS remains controversial and assessment and management are inconsistent. The needs of women with PCOS are not being adequately met and evidence practice gaps persist. Study Design, Size, DurationInternational evidence-based guideline development engaged professional societies and consumer organizations with multidisciplinary experts and women with PCOS directly involved at all stages. Appraisal of Guidelines for Research and Evaluation (AGREE) II-compliant processes were followed, with extensive evidence synthesis. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework was applied across evidence quality, feasibility, acceptability, cost, implementation and ultimately recommendation strength. Participants/Materials, Setting, MethodsGovernance included a six continent international advisory and a project board, five guideline development groups (GDGs), and consumer and translation committees. Extensive health professional and consumer engagement informed guideline scope and priorities. Engaged international society-nominated panels included pediatrics, endocrinology, gynecology, primary care, reproductive endocrinology, obstetrics, psychiatry, psychology, dietetics, exercise physiology, public health and other experts, alongside consumers, project management, evidence synthesis, and translation experts. Thirty-seven societies and organizations covering 71 countries engaged in the process. Twenty face-to-face meetings over 15months addressed 60 prioritized clinical questions involving 40 systematic and 20 narrative reviews. Evidence-based recommendations were developed and approved via consensus voting within the five guideline panels, modified based on international feedback and peer review, with final recommendations approved across all panels. Main Results and the Role of ChanceThe evidence in the assessment and management of PCOS is generally of low to moderate quality. The guideline provides 31 evidence based recommendations, 59 clinical consensus recommendations and 76 clinical practice points all related to assessment and management of PCOS. Key changes in this guideline include: (a) considerable refinement of individual diagnostic criteria with a focus on improving accuracy of diagnosis; (b) reducing unnecessary testing; (c) increasing focus on education, lifestyle modification, emotional wellbeing and quality of life; and (d) emphasizing evidence based medical therapy and cheaper and safer fertility management. Limitations, Reasons for CautionOverall evidence is generally low to moderate quality, requiring significantly greater research in this neglected, yet common condition, especially around refining specific diagnostic features in PCOS. Regional health system variation is acknowledged and a process for guideline and translation resource adaptation is provided. Wider Implications of the FindingsThe international guideline for the assessment and management of PCOS provides clinicians with clear advice on best practice based on the best available evidence, expert multidisciplinary input and consumer preferences. Research recommendations have been generated and a comprehensive multifaceted dissemination and translation program supports the guideline with an integrated evaluation program.Peer reviewe
Regulation of Amyloid Precursor Protein Processing by the Beclin 1 Complex
Autophagy is an intracellular degradation pathway that functions in protein and organelle turnover in response to starvation and cellular stress. Autophagy is initiated by the formation of a complex containing Beclin 1 (BECN1) and its binding partner Phosphoinositide-3-kinase, class 3 (PIK3C3). Recently, BECN1 deficiency was shown to enhance the pathology of a mouse model of Alzheimer Disease (AD). However, the mechanism by which BECN1 or autophagy mediate these effects are unknown. Here, we report that the levels of Amyloid precursor protein (APP) and its metabolites can be reduced through autophagy activation, indicating that they are a substrate for autophagy. Furthermore, we find that knockdown of Becn1 in cell culture increases the levels of APP and its metabolites. Accumulation of APP and APP C-terminal fragments (APP-CTF) are accompanied by impaired autophagosomal clearance. Pharmacological inhibition of autophagosomal-lysosomal degradation causes a comparable accumulation of APP and APP-metabolites in autophagosomes. Becn1 reduction in cell culture leads to lower levels of its binding partner Pik3c3 and increased presence of Microtubule-associated protein 1, light chain 3 (LC3). Overexpression of Becn1, on the other hand, reduces cellular APP levels. In line with these observations, we detected less BECN1 and PIK3C3 but more LC3 protein in brains of AD patients. We conclude that BECN1 regulates APP processing and turnover. BECN1 is involved in autophagy initiation and autophagosome clearance. Accordingly, BECN1 deficiency disrupts cellular autophagy and autophagosomal-lysosomal degradation and alters APP metabolism. Together, our findings suggest that autophagy and the BECN1-PIK3C3 complex regulate APP processing and play an important role in AD pathology
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