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Cadmium induces physiological and behavioral changes associated with 180 kDa NCAM lower expression and higher polysialic acid, in the African clawed Xenopus laevis tadpoles. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 273:116119. [PMID: 38382347 DOI: 10.1016/j.ecoenv.2024.116119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 02/16/2024] [Accepted: 02/17/2024] [Indexed: 02/23/2024]
Abstract
Heavy metals are released into the environment in increasing amounts from different natural and anthropogenic sources. Among them, cadmium contaminates aquatic habitats and represents a threat to Amphibians. To assess the risks of exposure to cadmium in the aquatic environment, we studied the survival rate of early tadpoles of Xenopus laevis under exposure to CdCl2 for 6 days in the concentration range between 0.15 and 150 µM of Cd2+. Tadpoles survived and reached stage 45 before feeding at all concentrations tested except 150 µM Cd2+, which significantly induced death. With an exposure of 15 µM Cd2+, tadpoles' mean body length decreased, heart rate increased, fastest swimming speed decreased, and distance traveled was greater compared to unexposed controls. Additionally, a witness of neuronal normal development, the neural cell adhesion molecules (NCAM) expression, was decreased. Moreover, this cell-surface glycoprotein exhibited higher polysialylation, a post-translational modification capable to reduce cell adhesion properties and to affect organ development. Our study highlights the effects of Cd2+ on a series of parameters including morphology, physiology, and behavior. They emphasize the deregulation of molecular NCAM suggesting this effector is an interesting biomarker to detect cadmic toxicity in early tadpoles.
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Follicular cells protect Xenopus oocyte from abnormal maturation via integrin signaling downregulation and O-GlcNAcylation control. J Biol Chem 2023; 299:104950. [PMID: 37354972 PMCID: PMC10366548 DOI: 10.1016/j.jbc.2023.104950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 06/09/2023] [Accepted: 06/16/2023] [Indexed: 06/26/2023] Open
Abstract
Xenopus oocytes are encompassed by a layer of follicular cells that contribute to oocyte growth and meiosis in relation to oocyte maturation. However, the effects of the interaction between follicular cells and the oocyte surface on meiotic processes are unclear. Here, we investigated Xenopus follicular cell function using oocyte signaling and heterologous-expressing capabilities. We found that oocytes deprotected from their surrounding layer of follicular cells and expressing the epidermal growth factor (EGF) receptor (EGFR) and the Grb7 adaptor undergo accelerated prophase I to metaphase II meiosis progression upon stimulation by EGF. This unusual maturation unravels atypical spindle formation but is rescued by inhibiting integrin β1 or Grb7 binding to the EGFR. In addition, we determined that oocytes surrounded by their follicular cells expressing EGFR-Grb7 exhibit normal meiotic resumption. These oocytes are protected from abnormal meiotic spindle formation through the recruitment of O-GlcNAcylated Grb7, and OGT (O-GlcNAc transferase), the enzyme responsible for O-GlcNAcylation processes, in the integrin β1-EGFR complex. Folliculated oocytes can be forced to adopt an abnormal phenotype and exclusive Grb7 Y338 and Y188 phosphorylation instead of O-GlcNAcylation under integrin activation. Furthermore, an O-GlcNAcylation increase (by inhibition of O-GlcNAcase), the glycosidase that removes O-GlcNAc moieties, or decrease (by inhibition of OGT) amplifies oocyte spindle defects when follicular cells are absent highlighting a control of the meiotic spindle by the OGT-O-GlcNAcase duo. In summary, our study provides further insight into the role of the follicular cell layer in oocyte meiosis progression.
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Diversity of sialic acids and sialoglycoproteins in gametes and at fertilization. Front Cell Dev Biol 2022; 10:982931. [PMID: 36340022 PMCID: PMC9630641 DOI: 10.3389/fcell.2022.982931] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 10/10/2022] [Indexed: 09/22/2023] Open
Abstract
Sialic acids are a family of 9-carbon monosaccharides with particular physicochemical properties. They modulate the biological functions of the molecules that carry them and are involved in several steps of the reproductive process. Sialoglycoproteins participate in the balance between species recognition and specificity, and the mechanisms of these aspects remain an issue in gametes formation and binding in metazoan reproduction. Sialoglycoproteins form a specific coat at the gametes surface and specific polysialylated chains are present on marine species oocytes. Spermatozoa are submitted to critical sialic acid changes in the female reproductive tract facilitating their migration, their survival through the modulation of the female innate immune response, and the final oocyte-binding event. To decipher the role of sialic acids in gametes and at fertilization, the dynamical changes of enzymes involved in their synthesis and removal have to be further considered.
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Acetylated lignin nanoparticles as a possible vehicle for photosensitizing molecules. NANOSCALE ADVANCES 2020; 2:5648-5658. [PMID: 36133893 PMCID: PMC9417530 DOI: 10.1039/d0na00615g] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 10/12/2020] [Indexed: 06/16/2023]
Abstract
Lignins are underused and abundant bio-sourced polymers with various potential applications. An attractive one is the development of nanoparticles for bioactive compound delivery. Here, we optimized the synthesis of hydrodispersible nanoparticles of acetylated lignin by comparing different lignin sources, degrees of acetylation and preparation methods. The formation of acetylated lignin nanoparticles in various solvents was probed by both experiments and, for the first time, a molecular dynamics simulation. We showed that dialysis is more suitable to obtain these nanoparticles than anti-solvent addition. The encapsulation of hydrophobic photosensitizing porphyrin in these nanoparticles was also demonstrated and rationalized at the molecular level, together with experiments, docking and molecular dynamics simulations. As acetylated lignin has been demonstrated to exhibit photosensitizing activity, the encapsulation of bioactive compounds in lignin nanoparticles opens the doors to a broad range of potential applications.
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A systematic review and meta-analysis of laparotomy compared with laparoscopic management of interstitial pregnancy. Facts Views Vis Obgyn 2020; 12:299-308. [PMID: 33575679 PMCID: PMC7863690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Interstitial pregnancy is a rare but life-threatening condition accounting for 1-4% of all types of tubal ectopic pregnancies. It can be managed by open and minimally invasive surgical techniques. Our goal was to compare laparoscopic and open surgery for managing interstitial pregnancy. SEARCH STRATEGY We searched PubMed, Scopus, Web of Science, and Cochrane up to May 2020. SELECTION CRITERIA 1) Women with interstitial pregnancy, 2) Intervention: laparoscopic surgery, 3) Comparator: open surgery, 4) Outcomes: Hospital stay, operation time, pain scale, blood loss. Secondary outcomes: any other reported 5) Study designs: interventional and observational. DATA COLLECTION AND ANALYSIS Data was extracted from the relevant articles and was pooled as mean difference (MD) or relative risk (RR) with a 95% confidence interval (CI). MAIN RESULTS We included six studies, three of which provided eligible data. The duration of hospital stay was lower in the laparoscopic surgery group (MD = -1.42, 95% CI [-1.72, -0.76], P < 0.0001). There was no significant difference in operative time (MD = 5.90, 95% CI [-11.30, 23.09], P = 0.50, blood loss (MD = -9.43, 95% CI [-214.18, 195.32], P = 0.93), complications (RR = 1.54, 95% CI [0.20, 11.85], P = 0.68), or blood transfusions (RR = 0.77, 95% CI [0.50, 1.25], P = 0.30). CONCLUSION Laparoscopic surgery is associated with shorter hospital stay, with no difference in terms of blood loss, post-, and intraoperative complications, and need for blood transfusion compared with laparotomy.
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Porphyrin-Loaded Lignin Nanoparticles Against Bacteria: A Photodynamic Antimicrobial Chemotherapy Application. Front Microbiol 2020; 11:606185. [PMID: 33281805 PMCID: PMC7705181 DOI: 10.3389/fmicb.2020.606185] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 10/20/2020] [Indexed: 01/29/2023] Open
Abstract
The need for alternative strategies to fight bacteria is evident from the emergence of antimicrobial resistance. To that respect, photodynamic antimicrobial chemotherapy steadily rises in bacterial eradication by using light, a photosensitizer and oxygen, which generates reactive oxygen species that may kill bacteria. Herein, we report the encapsulation of 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyrin into acetylated lignin water-dispersible nanoparticles (THPP@AcLi), with characterization of those systems by standard spectroscopic and microscopic techniques. We observed that THPP@AcLi retained porphyrin's photophysical/photochemical properties, including singlet oxygen generation and fluorescence. Besides, the nanoparticles demonstrated enhanced stability on storage and light bleaching. THPP@AcLi were evaluated as photosensitizers against two Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, and against three Gram-positive bacteria, Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis. THPP@AcLi were able to diminish Gram-positive bacterial survival to 0.1% when exposed to low white LED light doses (4.16 J/cm2), requiring concentrations below 5 μM. Nevertheless, the obtained nanoparticles were unable to diminish the survival of Gram-negative bacteria. Through transmission electron microscopy observations, we could demonstrate that nanoparticles did not penetrate inside the bacterial cell, exerting their destructive effect on the bacterial wall; also, a high affinity between acetylated lignin nanoparticles and bacteria was observed, leading to bacterial flocculation. Altogether, these findings allow to establish a photodynamic antimicrobial chemotherapy alternative that can be used effectively against Gram-positive topic infections using the widely available natural polymeric lignin as a drug carrier. Further research, aimed to inhibit the growth and survival of Gram-negative bacteria, is likely to enhance the wideness of acetylated lignin nanoparticle applications.
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Adverse effects of fly ashes used as immobilizing agents for highly metal-contaminated soils on Xenopus laevis oocytes survival and maturation-a study performed in the north of France with field soil extracts. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:3706-3714. [PMID: 30875069 DOI: 10.1007/s11356-019-04560-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 02/13/2019] [Indexed: 06/09/2023]
Abstract
Amphibians are now recognized as the most endangered group. One of this decline causes is the degradation of their habitat through direct contamination of water, soil leaching, or runoff from surrounding contaminated soils and environments. In the North of France, the extensive industrial activities resulted in massive soil contamination by metal compounds. Mineral amendments were added to soils to decrease trace metal mobility. Because of the large areas to be treated, the use of inexpensive industrial by-products was favored. Two types of fly ashes were both tested in an experimental site with the plantation of trees in 2000. Aim of the present work was to investigate the effects of extracts from metal-contaminated soils treated or not for 10 years with fly ashes on Xenopus laevis oocyte using cell biology approaches. Indeed, our previous studies have shown that the Xenopus oocyte is a relevant model to study the metal ion toxicity. Survival and maturation of oocyte exposed to the soil extracts were evaluated by phenotypic approaches and electrophysiological recordings. An extract derived from a metal-contaminated soil treated for 10 years with sulfo-calcic ashes induced the largest effects. Membrane integrity appeared affected and ion fluxes in exposed oocytes were changed. Thus, it appeared that extracted elements from certain mineral amendments used to prevent the mobility of metals in the case of highly metal-contaminated soils could have a negative impact on X. laevis oocytes.
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Effects of glyphosate and a commercial formulation Roundup® exposures on maturation of Xenopus laevis oocytes. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:3697-3705. [PMID: 30835066 DOI: 10.1007/s11356-019-04596-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 02/18/2019] [Indexed: 06/09/2023]
Abstract
Pesticides are often found at high concentrations in small ponds near agricultural field where amphibians are used to live and reproduce. Even if there are many studies on the impacts of phytopharmaceutical active ingredients in amphibian toxicology, only a few are interested in the earlier steps of their life cycle. While their populations are highly threatened with extinction. The aim of this work is to characterize the effects of glyphosate and its commercial formulation Roundup® GT Max on the Xenopus laevis oocyte maturation which is an essential preparation for the laying and the fertilization. Glyphosate is an extensively used herbicide, not only known for its effectiveness but also for its indirect impacts on non-target organisms. Our results showed that exposures to both forms of glyphosate delayed this hormone-dependent process and were responsible for spontaneous maturation. Severe and particular morphogenesis abnormalities of the meiotic spindle were also observed. The MAPK pathway and the MPF did not seem to be affected by exposures. The xenopus oocyte is particularly affected by the exposures and appears as a relevant model for assessing the effects of environmental contamination.
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Criteria for assessing the quality of mHealth apps: a systematic review. J Am Med Inform Assoc 2019; 25:1089-1098. [PMID: 29788283 DOI: 10.1093/jamia/ocy050] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 04/17/2018] [Indexed: 12/16/2022] Open
Abstract
Objective Review the existing studies including an assessment tool/method to assess the quality of mHealth apps; extract their criteria; and provide a classification of the collected criteria. Methods In accordance with the PRISMA statement, a literature search was conducted in MEDLINE, EMBase, ISI and Scopus for English language citations published from January 1, 2008 to December 22, 2016 for studies including tools or methods for quality assessment of mHealth apps. Two researchers screened the titles and abstracts of all retrieved citations against the inclusion and exclusion criteria. The full text of relevant papers was then individually examined by the same researchers. A senior researcher resolved eventual disagreements and confirmed the relevance of all included papers. The authors, date of publication, subject fields of target mHealth apps, development method, and assessment criteria were extracted from each paper. The extracted assessment criteria were then reviewed, compared, and classified by an expert panel of two medical informatics specialists and two health information management specialists. Results Twenty-three papers were included in the review. Thirty-eight main classes of assessment criteria were identified. These were reorganized by expert panel into 7 main classes (Design, Information/Content, Usability, Functionality, Ethical Issues, Security and Privacy, and User-perceived value) with 37 sub-classes of criteria. Conclusions There is a wide heterogeneity in assessment criteria for mHealth apps. It is necessary to define the exact meanings and degree of distinctness of each criterion. This will help to improve the existing tools and may lead to achieve a better comprehensive mHealth app assessment tool.
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ApiAppS: A Project to Study and Help Practitioners in Recommending mHealth Apps and Devices to Their Patients. Stud Health Technol Inform 2019; 264:1919-1920. [PMID: 31438407 DOI: 10.3233/shti190713] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The ApiAppS ongoing project aims to provide physicians with a decision support system for the prescription / recommendation of mHealth technologies. We describe the context and the components of the project which includes: 1) a technical part on modelling and implementing the decision support system, and 2) a psychosocial investigation part designed to have a better knowledge of general practitioners (GPs) and patients' expectations, beliefs and practices.
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Exposures to chemical contaminants: What can we learn from reproduction and development endpoints in the amphibian toxicology literature? ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 248:478-495. [PMID: 30831345 DOI: 10.1016/j.envpol.2019.02.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 01/09/2019] [Accepted: 02/04/2019] [Indexed: 06/09/2023]
Abstract
Environmental contamination is one of the major factors or cofactors affecting amphibian populations. Since 2000, the number of studies conducted in laboratory conditions to understand impacts of chemical exposures increased. They aimed to characterize biological effects on amphibians. This review proposes an overview of biological responses reported after exposures to metals, phytopharmaceuticals or emerging organic contaminants and focuses on endpoints relating to reproduction and development. Due to amphibian peculiar features, these periods of their life cycle are especially critical to pollutant exposures. Despite the large range of tested compounds, the same model species are often used as biological models and morphological alterations are the most studied observations. From the results, the laboratory-to-field extrapolation remained uneasy and exposure designs have to be more elaborated to be closer to environmental conditions. Few studies proposed such experimental approaches. Lastly, gametes, embryos and larvae constitute key stages of amphibian life cycle that can be harmed by exposures to freshwater pollutants. Specific efforts have to be intensified on the earliest stages and notably germ cells.
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Geografias animais: perspectivas anglo-saxãs, francesas e brasileiras. CONFINS 2018. [DOI: 10.4000/confins.16008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Synthesis and Studies of New Fluorescein-Porphyrin Dyads: A Theoretical and Experimental Approach. ChemistrySelect 2018. [DOI: 10.1002/slct.201802225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Effects of copper on the early development of Xenopus laevis: the case of CuSO 4 and Bordeaux mixture solutions. J Xenobiot 2018; 8:7809. [PMID: 30701063 PMCID: PMC6343105 DOI: 10.4081/xeno.2018.7809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 10/17/2018] [Indexed: 11/23/2022] Open
Abstract
Not available.
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A Cross-Sectional Study of Prominent US Mobile Health Applications: Evaluating the Current Landscape. AMIA ... ANNUAL SYMPOSIUM PROCEEDINGS. AMIA SYMPOSIUM 2018; 2017:715-723. [PMID: 29854137 PMCID: PMC5977729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Mobile health (mHealth) could offer unprecedented opportunity to provide medical support closer to the users. We have selected some relevant criteria to describe 100 apps from Google Play store and Apple's App Store's top suggestions in medical category. These characteristics were compared based on the paid or free nature of the apps, the target users: consumers or healthcare professionals, and the platform: Android or iOS. Seventeen provided functionalities and 27 medical subjects covered by these apps were also extracted. Our study shows that even in top rated mHealth apps, a high proportion lacks some basic criteria regarding the quality of the apps including the presence of a privacy policy, describing content sources, participation of the target users in the app development, etc. Paid apps did not ensure better quality compared to free apps. The current mHealth market is not mature enough to be used widely and recommended by healthcare professionals.
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Development of a Simple Hydroponic Assay to Study Vertical and Horizontal Resistance of Soybean and Pathotypes of Phytophthora sojae. PLANT DISEASE 2018; 102:114-123. [PMID: 30673456 DOI: 10.1094/pdis-04-17-0586-re] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Phytophthora root rot, caused by Phytophthora sojae, is one of the most damaging diseases of soybean and the introgression of Rps (Resistance to P. sojae) genes into elite soybean lines is arguably the best way to manage this disease. Current bioassays to phenotype the gene-for-gene relationship are hampered with respect to reproducibility and long-term stability of isolates, and do not accurately predict horizontal resistance individually. The aim of our study was to investigate a new way of phenotyping P. sojae isolates and vertical and horizontal resistance in soybean that relies on zoospores inoculated directly into a hydroponic system. Inoculation of P. sojae isolates against a set of eight differentials accurately and reproducibly identified pathotypes over a period of two years. When applied to test vertical resistance of soybean lines with known and unknown Rps genes, the bioassay relied on plant dry weight to correctly identify all genes. In addition, simultaneous inoculations of three P. sojae isolates, collectively carrying eight major virulence factors against 64 soybean lines with known and unknown levels of horizontal resistance, separated the plants into five distinct groups of root rot, allowing the discrimination of lines with various degrees of partial resistance. Based on those results, this bioassay offers several advantages in facilitating efforts in breeding soybean for P. sojae resistance and in identifying virulence factors in P. sojae.
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Maturation of Xenopus laevis oocytes under cadmium and lead exposures: Cell biology investigations. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2017; 193:105-110. [PMID: 29053961 DOI: 10.1016/j.aquatox.2017.10.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 09/25/2017] [Accepted: 10/14/2017] [Indexed: 06/07/2023]
Abstract
Since amphibians are recognised as good models to assess the quality of environments, only few studies have dealt with the impacts of chemical contaminants on their gametes, while toxic effects at this stage will alter all the next steps of their life cycle. Therefore, we propose to investigate the oocyte maturation of Xenopus laevis in cadmium- and lead-contaminated conditions. The impacts of cadmium and lead ions were explored on events involved in the hormone-dependent process of maturation. In time-course experiments, cadmium, at the highest concentration, delayed and prevented the germinal vesicle breakdown. Even in the absence of progesterone this ion could also induce it. No such spontaneous maturation was observed after lead exposures. An acceleration of the process at the highest tested concentration of lead (90μM), in presence of progesterone, was recorded. Cytological observations highlighted that cadmium exposures drove severe disturbances of meiotic spindle morphogenesis. At last, cadmium exposures altered the MAPK pathway, regarding the activation of ERK2 and RSK, but also the activation and the activity of the MPF, by disturbing the state of phosphorylation of Cdc2 and histone H3. Xenopus laevis oocytes were affected by these metal ion exposures, notably by Cd2+. Signatures of these metal exposures on the oocyte maturation were detected. This germ cell appeared to be a relevant model to assess the effects of environmental contaminants such as metals.
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New molecular systems for APDT in agronomy. Photodiagnosis Photodyn Ther 2017. [DOI: 10.1016/j.pdpdt.2017.01.096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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A Collaborative Evaluation Framework for Biometric Connected Devices in Healthcare. Stud Health Technol Inform 2017; 245:69-73. [PMID: 29295054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A large number of biometric connected devices are currently available with a variety of designs. Healthcare users cannot easily choose the reliable ones that correspond the best to their healthcare problems. The existing evaluation methods do not consider at the same time aspects of connectivity and healthcare usage. In this study, a collaborative evaluation framework for biometric connected devices in healthcare usage is proposed. This framework contains six dimensions: medical validity, technical reliability, usability, ergonomy, legal compliance, and accuracy of measurements. In a first step, these dimensions were assessed by designing a self administered questionnaire answered by the stakeholders (patients, health professionals, payers, and manufacturers). A case study was then carried out in a second step to test this framework in a project of telemonitoring for heart failure patients. The results are in favor of the efficiency of the proposed framework as a decision making tool in healthcare usage.
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mHealth Quality: A Process to Seal the Qualified Mobile Health Apps. Stud Health Technol Inform 2016; 228:205-209. [PMID: 27577372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A large number of mobile health applications (apps) are currently available with a variety of functionalities. The user ratings in the app stores seem not to be reliable to determine the quality of the apps. The traditional methods of evaluation are not suitable for fast paced nature of mobile technology. In this study, we propose a collaborative multidimensional scale to assess the quality of mHealth apps. During our process, the app quality is assessed in various aspects including medical reliability, legal consistency, ethical consistency, usability aspects, personal data privacy and IT security. A hypothetico-deductive approach was used in various working groups to define the audit criteria based on the various use cases that an app could provide. These criteria were then implemented into a web based self-administered questionnaires and the generation of automatic reports were considered. This method is on the one hand specific to each app because it allows to assess each health app according to its offered functionalities. On the other hand, this method is automatic, transferable to all apps and adapted to the dynamic nature of mobile technology.
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Adoption and Use of a Mobile Health Application in Older Adults for Cognitive Stimulation. Stud Health Technol Inform 2016; 221:13-17. [PMID: 27071867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Serious games could be used to improve cognitive functions in the elderly. We evaluated the adoption of a new tablet application dedicated to cognitive stimulation in the elderly. The Stim'Art application offers various serious games to work different cognitive functions (memory, attention, concentration, etc.). The usage of fifteen older adults was followed for six months. The type of the game, the number of launches for each game, the time spent on each game, the difficulty level, the success rate and perceived well-being of users have been studied and compared at the end of the first and the sixth months. The participants have played half an hour per day on average. The average time of playing per day in the sixth month was significantly higher than the average time of playing during the first month (p value < 7 * 10(-4)). The same result was found for the average number of game launches per day (p value < 7 * 10(-4)). However, older people seem not to launch more difficult levels in the last month. The success rate at sixth months was significantly higher than the success rate at the end of the first month (p value < 6.4 * 1010(-4)). Generally, seniors have had an improvement in their wellbeing score judged by themselves. Our study showed that the mobile application receives a good admission from users. The results are promising and can pave the way for improving cognitive function in the elderly patients. The use of tablets and the constitution of serious games in close cooperation with health professionals and elderly patients (the end user), are likely to provide satisfactory results to improve healthcare provided for elderly patients suffering from cognitive disorders.
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Mobile Health Applications, in the Absence of an Authentic Regulation, Does the Usability Score Correlate with a Better Medical Reliability? Stud Health Technol Inform 2015; 216:127-131. [PMID: 26262024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Health-related mobile applications (apps) have been shown to improve the quality of health and patient care. Their use in clinical and health-related environments is becoming more considerable. The number of health-related apps available for download has considerably increased, while the regulatory position of this new industry is not well known. Despite this lack of regulation, measuring the usability score of these apps is not difficult. We compared two samples of twenty health-related applications each. One of the samples contained the apps with top-rated usability scores, and the other contained the apps with lowest-rated usability scores. We found that a good usability score correlates with a better medical reliability of the app's content (p<0.005). In the period in which a valid regulation is still lacking, calculation and attribution of usability scores to mobile applications could be used to identify apps with better medical quality. However, the usability score method ought to be rigorous and should not be rounded off with a simple five stars rating (as is the case in the classic app stores).
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Toward a use case based classification of mobile health applications. Stud Health Technol Inform 2015; 210:175-179. [PMID: 25991125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Smartphones are growing in number and mobile health applications (apps) are becoming a commonly used way for improving the quality of health and healthcare delivery. Health related apps are mainly centralized in Medical and health&fitness categories in Google and Apple app stores. However, these apps are not easily accessible by the users. We decided to develop a system facilitating the access to these apps, to increase their visibility and usability. Various use cases for 567 health related apps in French were identified and listed incrementally. UML modeling was then used to represent these use cases and their relationships with each other and with the potential users of these apps. Thirty one different use cases were found that were then regrouped into six major categories: consulting medical information references, communicating and/or sharing the information, fulfilling a contextual need, educational tools, managing professional activities, health related management. A classification of this type would highlight the real purpose and functionalities of these apps and offers the user to search for the right app rapidly and to find it in a non-ambiguous context.
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Volatile, Isotope, and Organic Analysis of Martian Fines with the Mars Curiosity Rover. Science 2013; 341:1238937. [DOI: 10.1126/science.1238937] [Citation(s) in RCA: 327] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Abundance and Isotopic Composition of Gases in the Martian Atmosphere from the Curiosity Rover. Science 2013; 341:263-6. [PMID: 23869014 DOI: 10.1126/science.1237966] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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The DURAMAZ indicator system: a cross-disciplinary comparative tool for assessing ecological and social changes in the Amazon. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120475. [PMID: 23610180 PMCID: PMC3638440 DOI: 10.1098/rstb.2012.0475] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
During the last 20 years, the Amazon region has been at the same time a place of massive ecological and social change and a laboratory of experiments aimed at promoting sustainable development. Policies and project initiatives involving diverse social groups and environmental contexts have been implemented across the region. They have resulted in mixed outcomes and trade-offs between social and environmental dimensions, making their impact at the local level difficult to assess and their successes difficult to generalize. The objective of the DURAMAZ research project was to provide a better understanding of these impacts. It produced a multi-dimensional indicator system designed to allow a holistic view of sustainable development at local and subregional levels and a comparative perspective across 12 research sites, from an isolated indigenous village to smallholders and agribusiness areas in Mato Grosso. The results of the first observation campaign (2007-2009) show that despite the claim of promoting sustainable development, no project was able to untie the 'Gordian knot' of development in the Amazon. Communities continue to face the old dilemma of either enjoying a preserved ecosystem but enduring adverse life conditions, or enjoying better living at the expense of forest cover. Another finding is that the subregional context is very important in shaping the impacts of regional policies. Thus, the same policy will not always have the same effect, depending on in which context it is applied. Finally, we found that cultural factors and a sense of place play a more important role than economic factors when it comes to the way people evaluate their own situation. This research provides the basis for a second phase of the project (2012-2016) in which we will continue to expand our sample and to refine our methodologies with the goal of transforming the initiative into a network of observatories of sustainable development in the Amazon.
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Identification of genes potentially involved in the biocontrol activity of Pseudozyma flocculosa. PHYTOPATHOLOGY 2009; 99:1142-1149. [PMID: 19740027 DOI: 10.1094/phyto-99-10-1142] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Flocculosin is an antifungal cellobiose lipid linked to the biocontrol activity of Pseudozyma flocculosa and whose structure is very similar to that of ustilagic acid produced by Ustilago maydis. In this work, homologs of the U. maydis cyp1 gene, involved in the biosynthesis of ustilagic acid, were isolated and sequenced from P. flocculosa and P. fusiformata, the latter species being also known to produce ustilagic acid. Interestingly, no homologs were found in four other closely related Pseudozyma spp. from which no evidence of ustilagic acid production has ever been obtained, thus supporting the specificity of cyp1 with ustilagic acid synthesis. In addition, a homolog of the U. maydis uat1 gene involved in the acetylation of the molecule and located next to the cyp1 gene was partially sequenced from P. flocculosa. All three newly sequenced genes showed strong sequence similarity to their counterparts in U. maydis. Cyp1 expression was monitored in conditions that were either conducive or repressive to flocculosin production. Expression increased markedly (>100x) when P. flocculosa was inoculated in a growth medium conducive to flocculosin production but was rapidly downregulated in a repressive medium (in vitro) or on powdery mildew-infected cucumber leaves (in vivo). This suggests that the molecule was preferentially synthesized early in the process of searching for a growth substrate. This study provides the first identification of genes involved in the production of flocculosin, a molecule potentially associated with the biocontrol properties of P. flocculosa.
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Organic Synthesis in Soft Wall-Free Microreactors: Real-Time Monitoring of Fluorogenic Reactions. Anal Chem 2008; 80:6051-5. [DOI: 10.1021/ac800855u] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Alternative methods for genetic transformation of Pseudozyma antarctica, a basidiomycetous yeast-like fungus. J Microbiol Methods 2007; 70:519-27. [PMID: 17669528 DOI: 10.1016/j.mimet.2007.06.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 06/12/2007] [Accepted: 06/13/2007] [Indexed: 10/23/2022]
Abstract
Electroporation and Agrobacterium tumefaciens-mediated transformation (ATMT) were adapted and optimized for genetic transformation of the basidiomycetous yeast-like fungus Pseudozyma antarctica as alternatives to the cumbersome PEG/CaCl(2)-mediated transformation of protoplasts. Electroporation yielded 100-200 transformants per mug of DNA per 10(8) cells after 3 days on selective medium. For its part, ATMT yielded 60-160 transformants per 10(6) input cfu after 5-10 days on a selective medium. Transformants obtained from both methods showed stable hygromycin resistance and strong expression of green fluorescent protein. Analysis of integration events revealed a limited number of predominantly tandem insertions in the genome of transformants, an improvement over PEG/CaCl(2)-mediated transformation. Both protocols relied on intact conidia of P. antarctica as starting material and thus eliminated the need for cell wall-degrading or weakening agents such as lytic enzymes or chemicals. Other advantages over protoplast transformation included higher yield of transformants and shorter recovery time of transformed colonies on selective medium.
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Abstract
OBJECTIVES To describe 2 cases of adult Kawasaki Disease (KD) and to review the medical literature to better define the epidemiological, clinical, laboratory, histopathological, cardiovascular, and therapeutic aspects of adult KD compared with pediatric KD. METHODS Report of 2 cases, and review of the literature using a Medline search from 1967 to June 2003. RESULTS Including our 2 cases, there are 57 reports of adult KD, 74% among patients aged 18 to 30 years. Nine cases of KD associated with human immunodeficiency virus (HIV) infection were described, suggesting that an immunocompromised state may predispose to this syndrome. The incidence of specific diagnostic criteria was roughly similar in adults and in children. However, cheilitis, meningitis, and thrombocytosis were observed in a larger percentage of children, while arthralgia, adenopathy, and liver function abnormality were more common in adults. Although adult KD often was diagnosed after the acute phase, when a significant beneficial effect from gammaglobulin infusion could not be expected, this treatment did appear to shorten the course of the disease. Coronary aneurysms were less frequent in adults than in children. Prognosis was more favorable in adults, with less cardiovascular complications and no deaths. CONCLUSIONS Adult KD is a rare condition, which may go unrecognized. Other known disease processes with similar clinical presentations such as hypersensitivity drug reaction and toxic shock syndrome must be ruled out. For adult KD, exclusion criteria such as absence of hypotension, visceral impairment, staphylococcal infection, and any drug able to induce a drug hypersensitivity reaction are suggestive of the diagnosis, in the presence of the inclusion criteria, rash, conjunctival effusion, oropharynx changes, extremity changes, or adenopathy.
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[Impact of a continuous medical education on regional anaesthesia practice]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 2003; 22:379-86. [PMID: 12818337 DOI: 10.1016/s0750-7658(03)00101-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
Peripheral arterial disease (PAD) is most frequently caused by atherosclerosis. The prevalence of intermittent claudication is about 3 to 6% of the men over 60 years. But recent epidemiological studies demonstrate that prevalence of asymptomatic forms is two to three fold higher--about 3.4 to 12.1%. The most relevant diagnostic criteria for asymptomatic PAD is probably the measure of the ankle/brachial index. Most important risk factors for PAD are smoking and diabetes mellitus. Improving symptoms or stabilization are a common fate (50%) in PAD. About 25% will experience revascularization procedures (angioplasty or surgery), 4% will have severe amputation and worsening symptoms occur in 15% of patients. Critical limb ischemia is mostly rare (1%). It is not surprising that fate of claudicant and mortality is determined by coronary events and cardiovascular diseases.
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Abstract
Metal-dielectric coatings can be used successfully to design broadband absorbers. However, the understanding of the designs is not easy. Here we present a new analytical method using achromatic three-layer stacks. Such metal-dielectric basic structures permit movement from a fixed admittance value to another one over a wide spectral range. Efficient designs are calculated and explained with this method.
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Infrared optical filters for the infrared atmospheric sounding interferometer meteorological space instrument. APPLIED OPTICS 1999; 38:4182-4188. [PMID: 18323900 DOI: 10.1364/ao.38.004182] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Optical coatings are designed and produced for the Infrared Atmospheric Sounding Interferometer meteorological space instrument operating in the spectral range 3.5 15.5 m. First we discuss the choice of substrates and determine the complex refractive indices of thin-film materials. Then several theoretical solutions are studied for optimizing the efficiency of the instrument. To allow us to study the feasibility of the coatings, a specific mid-infrared optical monitoring system has been developed. This system is validated by the successful manufacture of two-cavity Fabry Perot filters.
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Chemical synthesis at solid interfaces. On the use of conducting polythiophenes equipped of adequate linkers allowing a facile and highly selective cathodic SN bond scission with a fully regenerating resin process. Tetrahedron 1998. [DOI: 10.1016/s0040-4020(98)00580-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Design and Manufacture of Low-Absorption ZnS-YF(3) Antireflection Coatings in the 3.5-16-num Spectral Range. APPLIED OPTICS 1998; 37:4239-4244. [PMID: 18285869 DOI: 10.1364/ao.37.004239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Broadband antireflection coatings on ZnSe substrates are designed and manufactured in the 3.5-16-mum IR range. The thin-film materials are YF(3) and ZnS produced by electron-beam deposition. To reach optimal performances to as great as 16 mum, we performed an accurate determination of complex indices, taking into account dispersion laws and absorption due to water within layers. With this knowledge, designs are optimized and absorption is reduced at 16 mum.
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Resuscitation with increasing doses of diaspirin crosslinked hemoglobin in swine. ARTIFICIAL CELLS, BLOOD SUBSTITUTES, AND IMMOBILIZATION BIOTECHNOLOGY 1996; 24:469-87. [PMID: 8879422 DOI: 10.3109/10731199609117440] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This study examined the effects of administering 0.5, 4, 10, and 30 mL/kg of Diaspirin Crosslinked Hemoglobin (DCLHb) in a swine model of non-lethal hemorrhagic shock. Thirty unanesthetized animals were bled (30 mL/kg, 1 mL/kg/min) and either recovered without treatment (Untreated Control, UC) or infused with 10 g/dL DCLHb (0.5, 4.0, 10 or 30 mL/kg at 1 mL/kg/min) or Lactated Ringer (LR, 90 mL/kg at 3 mL/kg/min). DCLHb caused dose-related increases in MAP. Both the 10 and 30 mL/kg doses of DCLHb increased MAP more than UC or LR. Lower doses of DCLHb and LR had effects on MAP similar to UC. After hemorrhage, CO increased in all groups. The effect of DCLHb on CO was dose-related. Only LR and 30 mL/kg of DCLHb transiently (through 90 min) increased CO more than UC. CO in animals given lower doses of DCLHb was comparable to UC. DCLHb (10 and 30 mL/kg) improved base excess and lactate concentrations, two indices of global perfusion, more rapidly and to a greater extent than either UC or LR. In this swine model of hemorrhage, even small doses of DCLHb exerted measurable beneficial effects on blood pressure and perfusion.
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Resuscitation with Diaspirin Crosslinked Hemoglobin in a pig model of hemorrhagic shock. ARTIFICIAL CELLS, BLOOD SUBSTITUTES, AND IMMOBILIZATION BIOTECHNOLOGY 1995; 23:39-61. [PMID: 7719445 DOI: 10.3109/10731199509117667] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The efficacy of Diaspirin Crosslinked Hemoglobin (DCLHb) as a resuscitative fluid in hemorrhagic shock was compared to another colloid solution (human serum albumin, HSA) and a crystalloid solution (Lactated Ringer's, LR). Hemorrhage (35 mL/kg) was followed by isovolemic exchange then volume replacement. This modeled the clinical situation where resuscitative fluids are administered prior to stopping the hemorrhage, the hemorrhage is stopped, then blood volume is restored. Four combinations of resuscitative fluids were evaluated during isovolemic exchange: volume replacement: DCLHb:LR, HSA:LR, HSA:HSA and LR:LR. All doses were 10 mL/kg:35 mL/kg except LR:LR which was 10 mL/kg:125 mL/kg. Volume replacement was followed by a stabilization period and reinfusion of shed blood (35 mL/kg). MAP increased most rapidly using DCLHb (from 48 to 102 mmHg after 10 min of isovolemic exchange) and was maintained for at least 2 hours. Arterial oxygen content and acid-base status were significantly improved after resuscitation with DCLHb:LR vs. other resuscitative therapies. In conclusion, DCLHb:LR was an effective resuscitative therapy in treatment of hemorrhagic shock.
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Abstract
Evidence for a presynaptic neuromodulatory effect of atrial natriuretic factor (ANF) has been obtained in rat adrenal pheochromocytoma cells (PC12), a clonal line that differentiates into adrenergic neuron-like cells when treated with nerve growth factor. ANF had no effect on basal norepinephrine (NE) release. In contrast, ANF markedly and significantly inhibited carbachol-induced NE release in a concentration-dependent manner. This result is consistent with the hypothesis that ANF may be an inhibitory neuromodulator.
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Abstract
Using modified microinfusion and free flow micropuncture techniques in the same intact and acutely thyroparathyroidectomized (TPTX) Munich-Wistar rats the nephron sites for phosphate reabsorption were reinvestigated. In intact animals, 62% of filtered phosphate was reabsorbed in the proximal tubule but none in the loop of Henle, here defined as the nephron segment between the last accessible proximal and the first distal convolution. Delivery of phosphate to the superficial distal tubule significantly exceeded urinary phosphate excretion but no phosphate reabsorption could be detected in the terminal nephron by distal microinfusions of radioactively labelled phosphate (32P). In TPTX rats, proximal phosphate reabsorption was enhanced and there was marked phosphate reabsorption in the loop of Henle. Similarly, 32P microinfused in the late proximal tubule was almost completely reabsorbed. Again, no phosphate tracer outflux was detected after distal microinfusion. It is concluded that phosphate reabsorption is confined to the proximal tubule and the loop of Henle.
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Saturation kinetics of phosphate reabsorption in rats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1977; 81:153-5. [PMID: 899925 DOI: 10.1007/978-1-4613-4217-5_18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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The postproximal site of phosphate reabsorption in presence and absence of parathyroid hormone. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1977; 81:149-51. [PMID: 899924 DOI: 10.1007/978-1-4613-4217-5_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Abstract
In this review current hypotheses for the regulation of filtration rate and the subsequent reabsorption of that filtrate by the proximal tubule are discussed. In the rat the filtration rate is highly plasma flow dependent because of the phenomenon of filtration equilibrium. On the other hand, in man and dog filtration rate is much less dependent on renal plasma flow. In these species glomerular capillary pressure rather than glomerular plasma flow may be the primary determinant of filtration. Three hypotheses for the autoregulation of glomerular filtration are discussed. Of these the myogenic theory, which holds that increases in perfusion pressure result in an intrinsic contraction of the smooth muscle in the walls of the afferent arterioles, remains the best, if not completely adequate, explanation for the phenomenon. The role of a macula densa feedback mechanism is controversial, although data are presented which strongly militate against this hypothesis. Similarly, the prostaglandins, although important in determining vascular resistance, probably do not mediate autoregulation. Two prevalent hypotheses for the regulation of fluid reabsorption by the proximal tubule, the physical factor hypothesis and the humoral hypothesis, are discussed. Data presented indicate that peritubule Starling forces have a marked effect on isotonic reabsorption by the proximal tubule in the presence of volume expansion and enhanced backleak into the proximal tubule lumen. However, in hydropenia and diminished backleak, changes in peritubule capillary Starling forces have little effect on proximal sodium reabsorption. Thus, the physical factor mechanism is a rather insensitive regulator of proximal reabsorption in the absence of volume expansion. Hormones known to regulate sodium transport per se, such as aldosterone, have no effect on sodium reabsorption by the proximal tubule. In contrast, those hormones primarily regulating anion reabsorption in the proximal tubule, such as parathyroid hormone, have significant effects on fluid reabsorption. Thus, the humoral regulation of anion reabsorption has secondary effects on proximal sodium reabsorption.
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