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At least 1,675 records · Page 93Linked to original sources

PubMed2005

[Positive end-expiratory pressure and tidal volume titration after recruitment maneuver in a canine model of acute respiratory distress syndrome].

OBJECTIVE: To investigate the mechanisms of alveolar derecruitment and titration of positive end-expiratory pressure (PEEP) and tidal volume (V(T)) after recruitment maneuver (RM) in acute respiratory distress syndrome (ARDS). METHODS: Eighteen dogs with oleic acid induced ARDS were ventilated with volume controlled ventilation [VCV, PEEP 16 cm H2O, V(T) 10 ml/kg, respiratory rate (RR) 30 breaths/min] and the steady state in this mode was defined as baseline (0 min). All animals accepted RM by using pressure controlled ventilation [PEEP 35 cm H2O and peak inspiratory pressure (PIP) 50 cm H2O for 1 min] and then randomly assigned into three groups and ventilated by VCV for 4 h: low V(T) and moderate PEEP group (LVMP group, V(T) 10 ml/kg, PEEP 16 cm H2O, RR 30 breaths/min), low V(T) and low PEEP group (LVLP group, V(T) 10 ml/kg, PEEP 10 cm H2O, RR 30 breaths/min) and moderate V(T) and low PEEP group (MVLP group, V(T) 15 ml/kg, PEEP 10 cm H2O, RR 20 breaths/min). Oxygenation, lung mechanics, hemodynamics and lung injury score were measured. RESULTS: (1) The average lower inflection pressure (LIP) was identified as (16.0 +/- 2.1) cm H2O. (2) PaO(2) in the LVMP group [(371 +/- 64) mm Hg at 30 min and (365 +/- 51) mm Hg at 60 min] was higher than that in the LVLP and the MVLP group [(243 +/- 112), (242 +/- 97) mm Hg at 30 min and (240 +/- 108), (232 +/- 87) mm Hg at 60 min, respectively; all P < 0.05], but no significant differences were observed among three groups from the second hour after RM to the end of the experiment. Better ventilation profiles were observed in the MVLP group. (3) Compared with baseline, marked cardiac compromise with higher airway plateau pressure (Pplat) and lower static respiratory compliance (Cst) were found in the LVMP group, while improvement was observed in other two groups. Cst in the MVLP group was slightly higher than that in the LVLP group. (4) No significant differences of lung injury were found from bronchoalveolar lavage fluid (BALF) analysis. CONCLUSIONS: Higher PEEP close to LIP maybe useful in preventing alveolar recollapse and improving oxygenation, but harmful to hemodynamics and may increase the risk of lung jury. Lower PEEP combined with moderate tidal volume after RM may be a more reasonable approach than conventional lung protective ventilation.

Animals↗

PubMedDate not supplied

[Use of potentiometric titration at constant pH for determination of the activity of lipoprotein lipase].

A method is developed for determination of the lipoprotein lipase activity. The method is based on the steady state potentiometric titration at constant pH value of higher fatty acids, liberated during the hydrolysis. An oil emulsion intralipid, activated by human blood serum, was used as a substrate. The sensitivity of the method was equal to 0.004-0.010 micronM of fatty acids per min. The reproducibility of the results was 2-5%. This simple and rapid method enabled to study kinetic of reactions, catalyzed by lipoprotein lipases.

Animals↗

PubMedDate not supplied

Youden analysis of Karl Fischer titration data from an interlaboratory study determining water in animal feed, grain, and forage.

Data from a recent interlaboratory study of the determination of water (moisture) in animal feed, grain, and forage (plant tissue) by Karl Fischer titration were re-analyzed using Youden plots. The purpose was to show the unique ability these plots possess of separating random and systematic errors visually while providing numerical estimates of the precision and the systematic error of the method. Furthermore, the usefulness of the technique is underscored because AOAC INTERNATIONAL allows the use of matched pairs in collaborative studies to obtain estimates of repeatability and reproducibility.

Animal Feed↗

PubMedDate not supplied

[Secretory IgA: quality control of the titration method].

In order to verify if the method for the titration of salivary secretory IgA (s-IgA) by the technical of radial immunodiffusion is trustworthy, have been carried out the precision tests in the series and among the series in two saliva samples with very different s-IgA concentrations, and precision and accuracy tests in the series and among the series using a solution with a known titre of IgA. The results of the first battery tests have shown a precision ranging from 93.04 to 95.43%. The results of the tests of the second battery have shown a precision ranging about 96% and an accuracy about 97%. The tested method is, therefore, sufficiently trustworthy.

Evaluation Studies as Topic↗

PubMed2005

Sensitivity of Aedes albopictus C6/36 cells line for the detection and infectivity titration of dengue virus.

Plaque assay procedure was carried out to determine the infectivity titration of dengue virus using Aedes albopictus C6/36 mosquito cell line. Cells were seeded in 6 wells plates and incubated until monolayer C6/36 cell lines were formed. Each well was exposed to a different dilution of dengue infected culture fluid, followed by addition of first and second overlay medium. Cells were observed under an inverted microscope and plaque staining was carried out. The results showed that countable plaques were not achieved and plaques formed were restricted to the central section due to the significant partial lysis of the C6/36 cells in the plates. However, the plaque assay technique using C6/36 cell line reported here appears to be promising and merits further detailed studies.

Aedes↗

PubMedDate not supplied

[Use of cross-absorbed sera in neutralization tests with viral titration by the cytopathogenic effect].

A new method for intratypic antigenic differentiation of poliovirus strains has been developed. The method is based on the use of cross-absorbed sera in neutralization tests where virus is titrated by the cytopathic effect. Qualitative differences between the antigenic structure of vaccine and "wild" strains as well as between some "wild" strains of the same serologic type have been found. The method may be used in practical laboratories.

Cytopathogenic Effect, Viral↗

PubMed2006

Dose titration of recombinant factor VIIa using thromboelastograph monitoring in a child with hemophilia and high titer inhibitors to factor VIII: a case report and brief review.

The administration of recombinant factor VIIa (rFVIIa) is complicated by a wide inter-subject variation in response, a short half-life, evolving indications for use, and the absence of a test that has been shown to correlate with clinical effect. This report describes a method used to titrate rFVIIa to thromboelastography (TEG) parameters in a difficult to manage hemophilic patient with high titer inhibition to factor VIII. The current concepts of monitoring rFVIla administration in hemophiliacs and uncontrolled hemorrhage in cardiac surgery are briefly reviewed.

Child↗

PubMed2006

[Study on the inclusion behavior of p-sulphonatocalix[4]arene with acridine by spectrofluorometric titrations].

p-sulphonatocalix[4] arene (1) was prepared according to the literature, and spectrofluorometric titrations were performed to investigate the inclusion behavior of (1) and acridine in citrate buffer solution (pH 5.92, 0.1 mol x L(-1)) at different temperatures. It was found that in definite concentration range, the emission peak of acridine exhibited a slight red shift and th fluorescence intensity decreased when (1) was added. They form stable host-guest complex, and the stoichiometry of the inclusion complex is 1 : 1. The stability constants of the inclusion complex at 15.0 degrees C, 20.0, 25.0 and 30.0 degrees C were determined as 3.08 x 10(5), 4.45 x 10(4), 2.58 x 10(4) and 8.90 x 10(3), respectively. The thermodynamic parameters of inclusion process, deltaG, deltaH and deltaS, were determined. The experimental results indicated that the inclusion process was an exothermic and enthalpy-driven process. It was found that the stability constants descended when temperature rose. The most probable pattern of the inclusion complex between (1) and acridine was proposed as: acridine partially goes into the cavity of (1), and the protonated N atom and the negatively charged sulphonyl group bond firmly owing to strong electrostatic interaction. With the main contribution of electrostatic interaction and the assistance of Van de Waals and hydrophobic interaction, the host and the guest molecules form 1 : 1 supramolecular complex.

English Abstract↗

PubMed2006

[Effect of lung stress index on titration of positive end-expiratory pressure at post-recruitment in three canine acute respiratory distress syndrome models].

OBJECTIVE: To investigate the relationship of lung stress index and positive end-expiratory pressure (PEEP) at post-recruitment in different canine acute respiratory distress syndrome (ARDS) models. METHODS: The ARDS models were induced by intravenous oleic acid, saline lavage and hydrochloric acid aspiration in anesthetized dogs. During volume control ventilation with constant inspiratory flow, PEEP was set to obtain a b (stress index) value between 0.9 and 1.1 (b = 1) before and post recruitment maneuver (RM). PEEP was changed to obtain b < 1 (0.6 < b < 0.8) and b > 1 (1.1 < b < 1.3). Meanwhile, the recruited volume (RV) was measured and pulmonary mechanics and gas exchange were observed. RESULTS: At b = 1 after RM, PEEP were (10.8 +/- 2.3), (12.8 +/- 1.8) and (9.2 +/- 1.8) cm H2O in the oleic acid, saline-lavaged and hydrochloric acid aspiration groups, respectively. PEEP in saline-lavaged group was higher than that in hydrochloric acid aspiration group (P < 0.05). The ratio of partial arterial oxygen tension and fraction of inspiratory oxygen (PaO(2)/FiO(2)) at b = 1 without RM was lower than those post-RM in all three groups (P < 0.05). In oleic acid group, PaO(2)/FiO(2) at b = 1 post-RM was (399 +/- 61) mm Hg, which was higher than that at b < 1 [(307 +/- 71) mm Hg], but there was no difference between those at b = 1 and b > 1. At b = 1 after RM, PaO(2)/FiO(2) in the saline-lavaged group was higher than that in acid aspiration group, but no difference between saline-lavaged group and oleic acid group was found. At b = 1 post-RM, RV were higher than that at b = 1 before RM in all three groups (P < 0.01), but there was no significant difference among three groups. At b = 1 post-RM in three groups, pulmonary compliance were higher than those at b > 1, but airway plateau pressure were lower than those at b > 1. CONCLUSIONS: Lung stress index could be a good indicator for PEEP titration at post-RM.

Animals↗

PubMed1990

Differential cross-tolerance to opioids in squirrel monkeys responding under a shock titration schedule.

The opioid agonists morphine, l-methadone, ethylketazocine, U50,488 and bremazocine were examined in squirrel monkeys responding under a schedule of shock titration before, during and after chronic morphine administration. Before chronic morphine administration, all drugs produced dose-dependent increases in median shock level (the intensity below which monkeys maintained shock 50% of the time). After approximately 6 weeks of daily morphine administration, dose-effect curves for the mu agonist morphine shifted to the right approximately 3/4 log unit. Dose-effect curves for the mu agonist l-methadone also shifted to the right, approximately 1/4 log unit. In contrast, dose-effect curves for the kappa agonist ethylketazocine did not shift during chronic morphine administration, whereas those for the kappa agonists U50,488 and bremazocine shifted to the left approximately 1/2 log unit. After termination of daily morphine administration, dose-effect curves returned toward their prechronic positions. The present study demonstrates that repeated administration of morphine produces tolerance to its antinociceptive effects, as well as cross-tolerance selective to other opioids possessing mu agonist properties. Morphine tolerance may be a useful procedure not only for distinguishing mu from kappa opioid antinociceptive activity in the squirrel monkey, but also for differentiating among kappa opioids that have varying degrees of mu agonist and antagonist activity.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMedDate not supplied

[EPR study of redox titration of Chromatium minutissimum chromatophores].

Redox titration of chromatophores through the region +300 +570 mV at room temperature results in generation of two dark ESR signals, a well-known reaction center signal and a new narrow line. This line is characterized by deltaH pp = 4.2 Oe, g-factor about that of RC and a Lorentzian shape. It is insensitive to illumination. The determination of an RC signal midpoint potential is affected by the presence of the narrow line. Taking into account the superposition of the two ESR signals it was measured to be +(486+/-+/-18)mV.

Bacterial Chromatophores↗

PubMed1979

Identification of four major classes of sulfhydryl groups in human blood platelets. Ferricyanide titration of spin-labeled platelets.

Human blood platelets have been labeled with the sulfhydryl-specific spin labels, 4-iodoacetamido-2,2,6,6-tetramethylpiperidine-1-oxyl and 3-maleimido-2,2,5,5-tetramethylpyrrolidine-1-oxyl. First, the ESR spectra of platelets labeled with either reagent revealed two classes of sulfhydryl groups, a mobile class and an immobile class. Second, when spin-labeled platelets were titrated with high concentrations of potassium ferricyanide (greater than 10(-3) M), there was a decrease in the peak heights of the mobile class of sulfhydryl groups due to dipole-dipole exchange. Third, plots of peak heights of the mobile class versus ferricyanide concentration revealed three classes of mobile sulfhydryl groups compared to a single immobile class. This technique may be used to show the relative locations of spin-labeled groups on cell surfaces.

Blood Platelets↗

PubMed1979

Equine infectious anemia virus: development of a simple reproducible method for titrating infectivity of the cell-adapted strain.

An equine dermal cell line between the 14th and 30th subpassages was used to develop a reproducible method of titrating the infectivity of the cell-adapted strain of equine infectious anemia virus (EIAV). Cells inoculated with EIAV were subcultured or fed once each week and were monitored for the production of P26 antigen of EIAV in supernatant fluids. Ultrathin sections were prepared once each week and were examined for the detection of budding virus-like particles (VLP). The VLP could not be detected in the infected cells subcultured once each week. When the medium was changed once week and when the cells not transferred, budding VLP were detected routinely after 3 to 4 weeks, Feeding of the infected cells once each week was used to establish the infectivity assay. The reproducibility of the assay on a frozen viral stock preparation was within an endpoint of one tenfold dilution.

Animals↗

PubMed1990

[24-hour blood pressure and renal function in cardiac failure during the titration phase of captopril and enalapril].

In 33 patients with heart failure (NYHA II-III) 24-h blood pressure was examined during the titration of two ACE-inhibitors. Blood pressure was measured by the oscillometric method using the blood pressure monitor 90202 from SpaceLabs, Inc. The measurements were taken from 06.00 to 22.00 hours every 20 min, and from 22.00 to 06.00 hours every 1 h. All patients received an additional therapy, either with captopril (group 1, n = 17) or enalapril (group 2, n = 16) in random order. Serum-electrolytes, serum-creatinine, and plasma-renin activity were measured before and during therapy with both ACE-inhibitors. 24-h blood pressure measurements were taken before and on the first and fifth day of the treatment with ACE-inhibitors. The groups did not different in respect to the degree of heart failure, the concomitant medication, or the 24-h profiles of blood pressure and heart rate. The mean initial doses of captopril was 9.2 +/- 1.2 mg. Each patient of group 2 received an initial dose of 2.5 mg enalapril. The maximal decrease of diastolic blood pressure occurred after 1 h in group 1 and after 4 h in group 2 and was similar in both groups (8 vs, 7 mmHg). The 24-h blood pressure values on day 5 were consistently below the pretreatment values (p less than 0.005). Heart rate was not affected by either ACE-inhibitor. The groups did not differ significantly during ACE-inhibition in their 24-h blood pressure and heart rate profiles. Before treatment, serum-sodium, -potassium and -creatinine were within the normal range.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

[Use of a titrated extract of Centella asiatica in chronic hepatic disorders (author's transl)].

The authors report their preliminary results of a study of the possible therapeutic activity of a titrated extract of Centella asiatica in chronic hepatic disorders. Early results are encouraging, especially from a histological point of view, where improvement in the criteria evaluated was noted in 5 of the 12 patients treated for the longest time. These results have to be assessed in a critical manner until confirmation is obtained by complementary studies.

Adult↗

PubMed1975

Evaluation of a new method for the intragastric titration of gastric juice.

A new method for the intragastric titration of hydrochloric acid with a pH sensitive telemetric antimone electrode connected via a receiver to an electronic trigger, which regulates a pump for the inflow of 1 M KHCO3 solution, was evaluated in 22 achlorhydric patients by a series of intragastric instillations of 0.1 N HCl. In vitro this procedure presented a high precision (r = 0.99). Under in vivo conditions a significant correlationship (r = 0.84, p = 0.001) between the input of hydrochloric acid and bicarbonate in a range from 1.4 to 16.7 mEq/30 min could be established in non-operated subjects. The average coefficient of variation was 34%. In subjects with partial gastrectomy (Billroth II) overtitration of 100% (y = 2.1 x -1.7, r = 0.78, p = 0.001) was recorded, suggesting an increased loss of bicarbonate related to the accelerated gastric evacuation.

Achlorhydria↗

PubMed1989

[A new approach to titrating active enzyme centers upon the use of surface-active micellar substances in organic solvents].

Micellar solutions of surfactant in organic solvents with rubber additions are proposed for determination of active enzyme concentration. A kinetic theory of enzymatic reactions in reversed micellar systems is developed, suggesting the intermicellar transport of the substrate to be the limiting step in viscous medium. Under these conditions, it is shown that fraction of the product formed after quick transformation of the substrate located in the enzyme-containing micelles depends upon active enzyme concentration and aggregation number of surfactant molecules. The proposed approach is used for the active-site titration of trypsin and cellobiase and for the determination of the aggregation number of Aerosol OT (AOT) molecules in the ternary system AOT/water/cyclohexane.

Binding Sites↗

PubMed1989

Indirect potentiometric titration of reducing carbohydrates. I. Using alkaline potassium mercuric bromide solution and sulphide selective electrode.

Indirect potentiometric titration of reducing carbohydrates was developed, where sugar is heated with excess of alkaline Hg(II)-bromide solution. The end point is detected potentiometrically using sulphide selective electrode. The effect of the alkalinity of the reagent, the heating period in a boiling water bath and the presence of the sucrose were studied. The statistical analysis of the results obtained by this method reveals that it can be used with the same accuracy as the Fehling' method.

Bromides↗