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Query: UMLS:C0085631 (agitation)
 12,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cells of Euglena gracilis Klebs var. bacillaris Cori mutant W3BUL grown in darkness on Hutner's pH 3.5 medium without agitation accumulate wax ester. These cells have undeveloped proplastid remnants characteristic of this mutant. If these cells are transferred to an inorganic medium and bubbled with 2-3% CO2 in air, the wax disappears and the proplastid expands and develops in darkness to form prolamellar bodies and membrane vessicles within 96 h. No further development takes place in darkness, but if these cultures are illuminated at 96 h formation of prothylakoids is observed. Thus the wax ester accumulated during growth can be used subsequently to support proplastid development up to the prolamellar body stage, but the formation of prothylakoids is strictly light-dependent. Development in this system takes place at a slower rate than in cells grown with shaking and lacking wax which are transferred to resting medium. As previously shown, all of proplastid development requires light under these conditions. It is suggested that the oxygen-requiring utilization of wax in darkness can provide energy and metabolites for a part of proplastid development but the later steps in these cells, or the entire development in cells lacking wax is supported by paramylum degradation which is strictly light-dependent. However, a specific light reaction required for prothylakoid organization is not ruled out.
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PMID:Light-independent and dependent phases of proplastid development in Euglena gracilis W3BUL. 311 30

An overview is given about the different variables which are of influence during platelet storage. After reinfusion of 51Cr-labeled platelets of PRP stored in first generation containers and evaluation of in vivo recovery and half life optimum, range of storage temperature was found to be 20-24 degrees C. Storage of PC in first generation containers showed a significant fall of pH which was in a clear relationship to platelet concentration, lactate production, and glucose consumption. If pH fell below 6.0 irreversible morphological changes and decrease of in vivo recovery/survival was observed. The second generation containers (PL-732, CLX, PL-1240) resulted in superior pH maintenance which was due to superior O2 and CO2 transport through the walls of the bags and a lower rate of glycolysis. In vivo recovery showed a gradual decline from 57% for fresh platelets to 42% after 7-day-storage. Platelet survival curves after 7-day-storage lay just at the lower limit of the range for fresh platelets. The success of prolonged storage depends critically on the mode of agitation used which was demonstrated by comparing three different agitators. A lot of questions remain still to be answered concerning the substrates of the oxidative metabolism, the morphological changes, and especially the in vitro function of platelets after prolonged storage.
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PMID:Platelet storage for transfusion. 375 17

We have developed a method to circumvent the use of exogenous proteolytic enzymes in the isolation of islets of Langerhans from the perinatal rodent pancreas. Advantage is taken of the propensity of fibroblastlike cells to attach and migrate on polystyrene at low-serum concentrations (5%). In contrast, at this serum level, rat islet epithelial cells tend not to adhere to the substrate. At 3 d of culture, islets are visible at the edges of the explants. With further fibroblast outgrowth the majority of islets are freefloating by 7 d. Simple agitation of the medium and centrifugation yields approximately 50 micrograms of islet tissue per perinatal pancreas. Further purification of the islets can be obtained by subculture. Rat islets can be maintained in this manner for several months in Medium F12 supplemented with 25% horse serum in an atmosphere of 5% CO2 and air at 37 degrees C. Hormone content of the islet tissue remains constant during prolonged subculture and such islets continue to exhibit appropriate insulin and glucagon responses to glucose and theophylline. The morphological integrity of the endocrine cells within the cultured islets was confirmed by immunocytochemistry and ultrastructural study. Nonendocrine cells are not identifiable within the long-term cultured islets.
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PMID:Nonenzymic in vitro isolation of perinatal islets of Langerhans. 613 59

Platelet aggregation can be measured quantitatively by continuous recording of the transmission of a beam of light across a suspension of platelets in constant agitation in an aggregometer. In routine clinical investigation, the study of platelet aggregation is performed on platelet-rich citrated plasma (PRPc). The blood sample has to be excellent to eliminate all traces of thrombin. The blood is collected in 3.8% sodium dihydrate citrate (1 volume for 9 volumes of blood). It is centrifuged at 190 g for 15 minutes at ambiant temperature. The PRPc obtained can be diluted with platelet-poor plasma (PPP) to adjust the concentration of platelets to 3 X 10(5)/microliters. The PRPc is stored at ambiant temperature in stoppered tubes under CO2 to avoid variations in pH. The maximal delay between the collection of the blood and the end of the study of aggregation is 3 hours. In certain cases, in order to define the platelet lesion and to eliminate the influence of plasma proteins, clotting factors and anti-coagulants, a suspension of washed platelets is used. The blood is collected on acid-citrate-dextrose (ACD) and centrifuged at + 37 degrees C to obtain the PRPc. The platelet deposit obtained by centrifugation of the PRPc is washed twice, according to Mustard's method, in Tyrode-albumin buffer at a concentration of 0.35% at + 37 degrees C. It is re-suspended in the same buffer solution at + 37 degrees C in the presence of apyrase and the platelet concentration is adjusted to 3 X 10(5)/microliters. The aggregation or agglutination of the platelets is induced by several agents: ADP, adrenalin, collagen, thrombin, arachidonic acid, ionophor A 23187, PAF-acether and ristocetin. The quantitative study of the aggregation curves of human platelets allows us to study the physiological and biochemical mechanisms control platelet aggregation, to recognize and classify the hereditary or acquired platelet abnormalities which lead to clinical haemorrhagic or thrombotic manifestations and to study the effect of drugs which inhibit platelet aggregation and to understand their mechanism of action.
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PMID:[Platelet aggregation: a tool for clinical investigation and pharmacological study. Methodology]. 635 9

The characteristics of an unclassified Mycobacterium sp. isolated from three patients with Crohn's disease are presented. The organism is extremely fastidious and mycobactin dependent and may require up to 18 months of incubation for primary isolation. Colony morphology is rough. Characteristics are unlike those of any presently defined species. The isolates produced postive niacin, catalase, and 2-week arylsulfatase reactions and were susceptible to neotetrazolium chloride (1:40,000), streptomycin (2 micrograms/ml), and rifampin (0.25 micrograms/ml). Chromogenicity, nitrate reduction, quantitative catalase, Tween hydrolysis, urease, tellurite reduction, pyrazinamidase, and 3-day arylsulfatase tests were negative, and the isolates were resistant to thiophene-2-carboxylic acid hydrazide (10 micrograms/ml) and isoniazid (10 micrograms/ml). Optimum growth in broth was determined to be in 7H9 medium with Dubos oleic albumin complex, Tween 80, and mycobactin J at 37 degrees C without CO2 or agitation and in low medium depth. This Mycobacterium sp. may be a subspecies or biovariant of Mycobacterium paratuberculosis, or it may represent a new species of Mycobacterium. It is suggested that this Mycobacterium sp. may play an etiological role in some cases of Crohn's disease.
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PMID:Characteristics of an unclassified Mycobacterium species isolated from patients with Crohn's disease. 651 78

Seven strains of Neisseria meningitidis have been grown in a commercial blood culture medium (supplemented peptone broth, Beckton-Dickinson) under five different atmospheric conditions (anaerobic, transiently vented, permanently vented in air, in 5% CO2 in air, and in air with agitation). Macroscopic evaluation was not a quick and reliable method to discover growth with this medium. With transient venting and under anaerobic conditions macroscopic growth was not detected at all and a loss in viability was observed. It is therefore recommended that frequent subcultures should be performed if meningococcal bacteraemia is suspected. Preliminary data indicate that agitation in air induces a more rapid growth than stationary incubation.
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PMID:Effect of atmosphere of incubation on the growth of Neisseria meningitidis in a blood culture medium. 678 44

A system has been developed for growth and maintenance of mammalian cells in suspension culture at high density. In principle, the maintenance of constant levels of required nutrients coupled with the removal of toxic cell byproducts can support much higher suspension cell densities than may be obtained in conventional spinners. The system consisted of 4- or 40-liter reaction vessels equipped with a vertically supported rotating cylindrical filter. Agitation was provided by the magnetically driven, rotating filter. Fresh medium was supplied at a rate of 10 to 20 ml/h per 10(9) cells and the expended medium free of cells was withdrawn through the rotating filter. Both pH and dissolved O2 and CO2 were monitored and regulated. Walker 256 carcinosarcoma cells have been grown in these reactors to densities 10- to 30-fold greater than that obtained in Bellco spinners. In addition to high cell densities, the yield of cells per liter of medium used was 2- to 3-fold that obtained in the conventional systems. Both 4- ad 40-liter reactor also has been operated without the use of antibiotics. The 40-liter reactor also has been modified for chemostat operation. In a single run, for example, the Walker cell density was maintained between 6 and 10 x 10(6) cells/ml with a total yield of 8.7 x 10(11) cells from 360 liters of medium.
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PMID:Large-scale rotating filter perfusion system for high-density growth of mammalian suspension cultures. 679 1

Metallic mercury has been assumed by several authors as not very reactive and, as a consequence, with little or no toxicity. The toxicity of this element is usually ascribed to alkyl-mercury ions considered to be formed by some microorganisms. In this work, we describe experiments that clearly show that metallic mercury can be easily oxidized by molecular oxygen in aqueous solution in the presence of species such as chloride, which complex Hg(II). The experiments were carried out using metallic mercury in NaCl aqueous solution under 'open air' (temperature and agitation rate maintained constant) and under more controlled conditions (CO2 rate bubbling, i.e. pH = 4.2; air rate bubbling, i.e., O2 constant concentration, temperature, agitation rate). The reactions were monitored spectrophotometricaly at 230 nm (HgCl2-(4)). Significative values of the concentration of Hg(II) in the form of HgCl2-(4) were soon attained in those solutions. For example, in 'open air' conditions, at 25 degrees C and [NaCl] = 30 g/l (0.51 mol/dm3), the maximal concentration of 13 ppm (6.44 x 10(-5) mol/dm3) of Hg(II) in the form of HgCl2-(4) was reached in 120 min; for [NaCl] = 5 g/l at 25 degrees C, (0.085 mol/dm3) the maximal concentration of 0.3 ppm (1.53 x 10(-6) mol/dm3) of Hg(II) in the form of HgCl2-(4) was reached in 10 min. The rate constants, kobs, of the oxidation of the metallic mercury under the studied conditions are pseudo zero-order at 25 degrees C, and under more controlled conditions have ranged from 1.0 x 10(-7) mol/min ([NaCl] = 5 g/l identical to 0.085 mol/dm3) to 20.0 x 10(-7) mol/min ([NaCl] = 300 g/l identical to 5.12 mol/dm3). The rate constant increases with temperature, up to 25 degrees C, from where kobs remains constant up to 40 degrees C. From the analysis of the experimental results it was possible to propose a mechanism of oxidation of metallic mercury by O2 in aqueous solution containing NaCl. This oxidation is proposed as a possible route for the introduction of mercury into biological systems.
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PMID:A possible path for mercury in biological systems: the oxidation of metallic mercury by molecular oxygen in aqueous solutions. 748 43

We hypothesized that obese children with a history of breathing difficulty during sleep would demonstrate (1) evidence of complete and partial obstructive sleep apnea (OSA) with hypercarbia and/or hypoxemia; and (2) correlation between symptoms, degree of obesity, adenoid and tonsil size, and polysomnography (PSG) results. We evaluated 32 obese children [% ideal body weight (IBW), 196 +/- 45%] with a sleep history questionnaire, airway radiographs, electrocardiograms (ECG), and PSG. By history, we found snoring (100%), difficulty breathing (59%), sweating (44%), restlessness (53%), arousals (41%), apnea (50%), worsening with upper respiratory infection (URI) (81%), hypersomnolence (59%), and mouth breathing (59%). We found adenoid and/or tonsil enlargement on 75% of airway x-ray pictures. ECGs were abnormal in 5 patients. Among all patients, mean sleep study oxyhemoglobin saturation (SaO2) was 85 +/- 16% and mean end-tidal CO2 (PetCO2) was 51 +/- 7 torr; 84% had paradoxical inward movement of the chest on inspiration, 59% had OSA, and 66% had partial OSA. In those with > or = 200% IBW and adenotonsillar enlargement, elevated PetCO2 and the presence of hypoxemia (SaO2 < 90%) for > or = 5% of the total sleep time (TST) were correlated, unlike in patients of similar weight but without adenotonsillar enlargement. Individuals symptoms did not correlate with the severity of PSG abnormalities. By discriminant analysis, using three variables (IBW, presence of adenotonsillar tissue, and presence of > or = 5 symptoms), we could predict PSG abnormalities with up to 81% reliability. Our findings indicate that in obese children, particularly those with %IBW > or = 200 and adenotonsillar hypertrophy, with sleep-disordered breathing evaluation by polysomnography should be considered.
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PMID:Polysomnography in obese children with a history of sleep-associated breathing disorders. 836 18

The kinetics and efficiency of carbon dioxide recovery in modern versions of the Sturm Ready Biodegradation Test were examined to determine the ability of CO2 evolution measurements to accurately estimate the rate and extent of ultimate biodegradation (mineralization). Kinetic data were analyzed by nonlinear regression techniques using an automated curve-fitting package available from commercial sources. The kinetics of CO2 recovery in standard 3.8 L glass carboys containing 2 L of medium were rapid when headspace aeration (approximately 6 ml/min) and moderate agitation (140 rev/min) on a rotary platform shaker were used to ensure adequate aeration and mixing. The time (half-life) for 50% CO2 recovery in external base traps was 4-5 hours, and stoichiometric recoveries of CO2 equivalents added as bicarbonate were obtained within 24 hours. The kinetics of CO2 evolution during biodegradation of several test compounds were significantly slower than the kinetics of CO2 recovery, with half-lives between 65 and 191 hours. Our results indicate that mass transfer limitations do not impact CO2 recoveries or biodegradation kinetic measurements in modern versions of the Sturm Test, even in test vessels with relatively low surface area to volume ratios (1:1). The use of headspace aeration and mixing generates reliable kinetic data, which can be analyzed by commercially-available nonlinear regression packages to provide rate information for the classification of chemicals with different biodegradation profiles.
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PMID:Carbon dioxide recovery in ready biodegradation tests: mass transfer and kinetic considerations. 878 99


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