965 resultados para 14Carbon uptake per cell rate
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Rate of CO2 assimilation was determined above the Broken Spur and TAG active hydrothermal fields for three main ecosystems: (1) hydrothermal vents; (2) 300 m near-bottom layer of plume water; and (3) bottom sediments. In water samples from warm (40-45°C) vents assimilation rates were maximal and reached 2.82-3.76 µg C/l/day. In plume waters CO2 assimilation rates ranged from 0.38 to 0.65 µg C/l/day. In bottom sediments CO2 assimilation rates varied from 0.8 to 28.0 µg C/l/day, rising up to 56 mg C/kg/day near shrimp swarms. In the most active plume zone of the long-living TAG field bacterial production of organic matter (OM) from carbonic is up to 170 mg C/m**2/day); production of autotrophic process of bacterial chemosynthesis reaches about 90% (156 mg C/m**2/day). Thus, chemosynthetic production of OM in September-October is almost equal to that of photosynthetic production in the oceanic region. Bacterial production of OM above the Broken Spur hydrothermal field is one order lower and reaches only 20 mg C/m**2/day.
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Bennett Champ Clark, chairman of subcommittee.
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Approximately 15% of a population of the cryopelagic nototheniid fish Pagothenia borchgrevinki, found constantly swimming immediately beneath the annual fast ice, in McMudro Sound. Ross Sea, Antarctica, was affected by X-cell gill disease. This disease affected blood flow through the gill lamellae, and this in turn affected oxygen uptake. Exercise caused increases in heart rate and ventral aortic blood pressure. Heart rate increased from 15.1 +/- 1.55 to 23.1 +/- 0.93 beats min(-1) in healthy fish, with a similar increase from 15.1 +/- 1.55 to 23.1 +/- 0.93 beats min(-1) in healthy fish, with a similar increase (to 24.6 +/- 0.26 beats min(-1)) in X-cell-affected animals. In healthy fish, pressures rose with exercise (from 2.72 +/- 0.11 to 3.75 +/- 0.19 kPa) and then rapidly returned to resting levels during recovery. In X-cell fish pressures rose during exercise, but then continued to rise, to reach a high of 4.18 +/- 0.13 kPa, close to the predicted maximum pressure able to be generated by these hearts. Recovery was rapid in healthy fish, but was prolonged in diseased animals. As they are constantly swimming, there is the potential that X-cell-affected fish suffer from chronic hypertension. (C) 2003 The Fisheries Society of the British Isles.
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Receptor-mediated endocytosis is a constitutive high capacity pathway for the reabsorption of proteins from the glomerular filtrate by the renal proximal tubule. ClC-5 is a voltage-gated chloride channel found in the proximal tubule where it has been shown to be essential for protein uptake, based on evidence from patients with Dent's disease and studies in ClC-5 knockout mice. To further delineate the role of ClC-5 in albumin uptake, we performed a yeast two-hybrid screen with the C-terminal tail of ClC-5 to identify any interactions of the channel with proteins involved in endocytosis. We found that the C-terminal tail of ClC-5 bound the actin depolymerizing protein, cofilin, a result that was confirmed by GST-fusion pulldown assays. In cultured proximal tubule cells, cofilin was distributed in nuclear, cytoplasmic, and microsomal fractions and co-localized with ClC-5. Phosphorylation of cofilin by overexpressing LIM kinase 1 resulted in a stabilization of the actin cytoskeleton. Phosphorylation of cofilin in two proximal tubule cell models (porcine renal proximal tubule and opossum kidney) was also accompanied by a pronounced inhibition of albumin uptake. This study identifies a novel interaction between the C-terminal tail of ClC-5 and cofilin, an actin-associated protein that is crucial in the regulation of albumin uptake by the proximal tubule.
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We have employed an inverse engineering strategy based on quantitative proteome analysis to identify changes in intracellular protein abundance that correlate with increased specific recombinant monoclonal antibody production (qMab) by engineered murine myeloma (NSO) cells. Four homogeneous NSO cell lines differing in qMab were isolated from a pool of primary transfectants. The proteome of each stably transfected cell line was analyzed at mid-exponential growth phase by two-dimensional gel electrophoresis (2D-PAGE) and individual protein spot volume data derived from digitized gel images were compared statistically. To identify changes in protein abundance associated with qMab clatasets were screened for proteins that exhibited either a linear correlation with cell line qMab or a conserved change in abundance specific only to the cell line with highest qMab. Several proteins with altered abundance were identified by mass spectrometry. Proteins exhibiting a significant increase in abundance with increasing qMab included molecular chaperones known to interact directly with nascent immunoglobulins during their folding and assembly (e.g., BiP, endoplasmin, protein disulfide isomerase). 2D-PAGE analysis showed that in all cell lines Mab light chain was more abundant than heavy chain, indicating that this is a likely prerequisite for efficient Mab production. In summary, these data reveal both the adaptive responses and molecular mechanisms enabling mammalian cells in culture to achieve high-level recombinant monoclonal antibody production. (C) 2004 Wiley Periodicals, Inc.
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Background. Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists. which are known to be critical factors in lipid metabolism, have also been reported to reduce proteinuria. The mechanism and its relevance to progressive nephropathy have not been determined. The aims of this study were to assess the direct effects of a PPARgamma agonist on tubular cell albumin uptake, proinflammatory and profibrotic markers of renal pathology, using an opossum kidney model of proximal tubular cells. Methods. Cells were exposed to pioglitazone (10 mumol/L) in the presence and absence of low-density lipoprotein (LDL) 100 mug/mL +/- exposure to albumin 1 mg/mL. Results were expressed relative to control (5 mmol/L glucose) conditions. Results. Pioglitazone caused a dose-dependent increase in tubular cell albumin uptake (P < 0.0001). Despite the increase in albumin reabsorption, no concurrent increase in inflammatory or profibrotic markers were observed. Exposure to LDL increased monocyte chemoattractant protein-1 (MCP-1) (P < 0.05) and transforming growth factor-beta1 (TGF-beta1) (P < 0.05) production. which were reversed in the presence of pioglitazone. LDL induced increases in MCP-1 and TGF-β1 were independent of nuclear factor-κB (NF-κB) transcriptional activity. In contrast. tubular exposure to albumin increased tubular protein uptake, in parallel with an increase in MCP-1 (P = 0.05): TGF-β1 (P < 0.02) and NF-kappaB transcriptional activity (P < 0.05). which were unaffected by concurrent exposure to pioglitazone. Conclusion. These findings suggest that dyslipidemia potentiates renal pathology through mechanisms that may be modified PPARγ activation independent of NF-κB transcriptional activitv. In contrast, tubular exposure to protein induces renal damage through NF-κB-dependent mechanisms that are Unaffected by PPARγ activation.
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Soft tissue engineering presents significant challenges compared to other tissue engineering disciplines such as bone, cartilage or skin engineering. The very high cell density in most soft tissues, often combined with large implant dimensions, means that the supply of oxygen is a critical factor in the success or failure of a soft tissue scaffold. A model is presented for oxygen diffusion in a 15-60 mm diameter dome-shaped scaffold fed by a blood vessel loop at its base. This model incorporates simple models for vascular growth, cell migration and the effect of cell density on the effective oxygen diffusivity. The model shows that the dynamic, homogeneous cell seeding method often employed in small-scale applications is not applicable in the case of larger scale scaffolds such as these. Instead, we propose the implantation of a small biopsy of tissue close to a blood supply within the scaffold as a technique more likely to be successful. Crown Copyright (c) 2005 Published by Elsevier Ltd. All rights reserved.
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Background The use of sunscreens on the skin can prevent sunburn but whether long-term use can prevent skin cancer is not known. Also, there is evidence that oral betacarotene supplementation lowers skin-cancer rates in animals, but there is limited evidence of its effect in human beings. Methods In a community-based randomised trial with a 2 by 2 factorial design, individuals were assigned to four treatment groups: daily application of a sun protection factor 15-plus sunscreen to the head, neck, arms, and hands, and betacarotene supplementation (30 mg per day); sunscreen plus placebo tablets; betacarotene only; or placebo only. Participants were 1621 residents of Nambour in southeast Queensland, Australia. The endpoints after 4.5 years of follow-up were the incidence of basal-cell and squamous-cell carcinomas both in terms of people treated for newly diagnosed disease and in terms of the numbers of tumours that occurred. Analysis of the effect of sunscreen was based only on skin cancers that developed on sites of daily application. All analyses were by intention to treat. Findings 1383 participants underwent full shin examination by a dermatologist in the follow-up period. 250 of them developed 758 new skin cancers during the follow-up period. There were no significant differences in the incidence of first new shin cancers between groups randomly assigned daily sunscreen and no daily sunscreen (basal-cell carcinoma 2588 vs 2509 per 100 000; rate ratio 1.03 [95% CI 0.73-1.46]; squamous-cell carcinoma 876 vs 996 per 100 000; rate ratio 0.88 [0.50-1.56]). Similarly, there was no significant difference between the betacarotene and placebo groups in incidence of either cancer (basal-cell carcinoma 3954 vs 3806 per 100 000; 1.04 [0.73-1.27]; squamous-cell carcinoma 1508 vs 1146 per 100 000; 1.35 [0.84-2.19]). In terms of the number of tumours, there was no effect on incidence of basal-cell carcinoma by sunscreen use or by betacarotene but the incidence of squamous-cell carcinoma was significantly lower in the sunscreen group than in the no daily sunscreen group (1115 vs 1832 per 100 000; 0.61 [0.46-0.81]). Interpretation There was no harmful effect of daily use of sunscreen in this medium-term study. Cutaneous squamous-cell carcinoma, but not basal-cell carcinoma seems to be amenable to prevention through the routine use of sunscreen by adults for 4.5 years. There was no beneficial or harmful effect on the rates of either type of skin cancer, as a result of betacarotene supplementation.
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Oxidised LDL accumulates in macrophages following scavenger receptor (SR) uptake. The expression of the SR, CD36, is increased by oxidised LDL. The signalling molecule, ceramide, can modulate intracellular peroxides and increase lipid peroxidation. Ceramide also accumulates in atherosclerotic plaques. Thus, we have examined whether ceramide can modulate CD36 expression and function in human monocyte/macrophages. Addition of synthetic short chain ceramides or the action of sphingomyelinase to generate physiological long chain ceramides in situ caused significant reductions in CD36 expression by monocytes/macrophages which was not due to inhibition of mRNA expression. Inhibition of proteasomal degradation using lactacystin had no effect on CD36 expression, however, flow cytometric analysis of permeabilised cells suggested an intracellular trafficking blockade. Ceramide treated monocytes/macrophages showed dose dependent reduction in oxidised LDL uptake. Taken together, it is suggested that ceramide blocks the transport of CD36 to the membrane of monocytes/macrophages, thereby preventing uptake of oxidised LDL. © 2006 Elsevier Inc. All rights reserved.
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Investigations were undertaken to study the role of the protein cross-linking enzyme tissue transglutaminase in changes associated with the extracellular matrix and in the cell death of human dermal fibroblasts following exposure to a solarium ultraviolet A source consisting of 98.8% ultraviolet A and 1.2% ultraviolet B. Exposure to nonlethal ultraviolet doses of 60 to 120 kJ per m2 resulted in increased tissue transglutaminase activity when measured either in cell homogenates, "in situ" by incorporation of fluorescein-cadaverine into the extracellular matrix or by changes in the epsilon(gamma-glutamyl) lysine cross-link. This increase in enzyme activity did not require de novo protein synthesis. Incorporation of fluorescein-cadaverine into matrix proteins was accompanied by the cross-linking of fibronectin and tissue transglutaminase into nonreducible high molecular weight polymers. Addition of exogenous tissue transglutaminase to cultured cells mimicking extensive cell leakage of the enzyme resulted in increased extracellular matrix deposition and a decreased rate of matrix turnover. Exposure of cells to 180 kJ per m2 resulted in 40% to 50% cell death with dying cells showing extensive tissue transglutaminase cross-linking of intracellular proteins and increased cross-linking of the surrounding extracellular matrix, the latter probably occurring as a result of cell leakage of tissue transglutaminase. These cells demonstrated negligible caspase activation and DNA fragmentation but maintained their cell morphology. In contrast, exposure of cells to 240 kJ per m2 resulted in increased cell death with caspase activation and some DNA fragmentation. These cells could be partially rescued from death by addition of caspase inhibitors. These data suggest that changes in cross-linking both in the intracellular and extracellular compartments elicited by tissue transglutaminase following exposure to ultraviolet provides a rapid tissue stabilization process following damage, but as such may be a contributory factor to the scarring process that results.
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The aim of this thesis is to investigate the physicochemical parameters which can influence drug loading within liposomes and to characterise the effect such formulations have on drug uptake and transport across in vitro epithelial barrier models. Liposomes composed of phosphatidylcholine (PC) or distearoyl phosphatidylcholine (DSPC) and cholesterol (0, 4, 8, 16 µM) were prepared and optimised in terms of drug loading using the hand-shaking method (Bangham et al., 1965). Subsequently, liposomes composed of 16 µM PC or DSPC and cholesterol (4 µM) were used to monitor hydroxybenzoate release and transport from Iiposomes. The MIT (3[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) and crystal violet assays were employed to determine toxicity of the Iiposome. formulations towards the Caco-2 cell line, employed to model the epithelial barrier in vitro. Uptake and transport of mannitol, propranolol, glutamine and digoxin was measured in the presence and absence of Iiposome formulations to establish changes in absorption resulting from the presence of lipid formulations. Incorporation of the four hydroxybenzoates was shown to be influenced by a number of factors, including liposome composition and drug conformation. Methyl hydroxybenzo.ate (MP) was incorporated into the bilayer most effectively with percentage incorporation of 68% compared to 45% for butyl hydroxybenzoate (BP), despite its increased Iipophilicity. This was attributed to the decreased packing ability of BP within the hydrocarbon core of the lipid bilayer compared to MP. Release studies also suggested that the smaller MP was more strongly incorporated within the lipid bilayer with only 8% of the incorporated solute being released after 48-hours compared to 17% in the case of BP. Model transport studies were seen to reflect drug release profiles from the liposome bilayers with significantly (p < 0.01) higher amounts of BP partitioning from the liposome compared to MP, Caco-2 cell viability was maintained above 86% in the presence of all Iiposome formulations tested indicating the liposome formulations are non-toxic towards Caco-2 cells. Paracellular (apical-to-basolateral) transport of mannitol was significantly increased in the presence of DSPC, PC / DSPC:Cholesterol (16:4 µM; 1000 µg). Glutamine uptake and transport via the carrier-mediated route was Significantly (p < 0.01) increased in the presence of PC I DSPC:Cholesterol (16:0; 16:4 µM). Digoxin apical-to-basolateral transport was significantly increased (p < 0,01) in the presence of PC / DSPC:Cholesterol (16:0; 16:4 µM); thus reducing digoxin efflux via P-glycoprotein. In contrast, PC:ChoJesterol (16:0; 16:4 µM) significantly (p < 0.01) decreased propranolol uptake via the passive transcellular route. Bi-directional transport of propranolol was significantly (p < 0,01) decreased in the presence of PC/DSPC:Cholesterol (16:0; 16:4 µM). The structure of a solute is an important determinant for the incorporation and release of a solute from liposome formulations. PC, DSPC and cholesterol liposome formulations are nontoxic towards Caco-2 cell monolayers and improved uptake and transport of mannitol, glutamine. and digoxin across Caco-2 cell monolayers; thus providing a potential alternative delivery vehicle.
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The mechanism behind the immunostimulatory effect of the cationic liposomal vaccine adjuvant dimethyldioctadecylammonium and trehalose 6,6′- dibehenate (DDA:TDB) has been linked to the ability of these cationic vesicles to promote a depot after administration, with the liposomal adjuvant and the antigen both being retained at the injection site. This can be attributed to their cationic nature, since reduction in vesicle size does not influence their distribution profile yet neutral or anionic liposomes have more rapid clearance rates. Therefore the aim of this study was to investigate the impact of a combination of reduced vesicle size and surface pegylation on the biodistribution and adjuvanticity of the formulations, in a bid to further manipulate the pharmacokinetic profiles of these adjuvants. From the biodistribution studies, it was found that with small unilamellar vesicles (SUVs), 10% PEGylation of the formulation could influence liposome retention at the injection site after 4 days, whilst higher levels (25 mol%) of PEG blocked the formation of a depot and promote clearance to the draining lymph nodes. Interestingly, whilst the use of 10% PEG in the small unilamellar vesicles did not block the formation of a depot at the site of injection, it did result in earlier antibody response rates and switch the type of T cell responses from a Th1 to a Th2 bias suggesting that the presence of PEG in the formulation not only control the biodistribution of the vaccine, but also results in different types of interactions with innate immune cells. © 2012 Elsevier B.V.
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The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.
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Radiotherapy (RT) has recently evolved with the emergence of heavy ion radiations or new fractionation schemes of photon therapy, which modify the dose rate of treatment delivery. The aim of the present study was then to evaluate the in vitro influence of a ultra-high dose rate comparing them with standard dose rate. In this regard, a radioresistant SK-MEL-28 cell line were irradiated with x-ray in order to have a total dose of 2 and 4 Gy, at two different dose rate. The ultra-high dose rate is a specific property of the dense plasma focus (DPF) device, which has pulsed operation and thus gives short and highly energetic pulses of multiple types of rays and particles, in this case, we focused our study on the influence of X-rays. While a low dose rate is obtained with conventional X-ray tube. In this study it results that a ultra-high dose rate enhances radiosensitivity of melanoma cells while reducing the adhesion, proliferation and migration ability of cells.