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PubMed1975

Dose titration of steroidal and non-steroidal topical anti-inflammatory agents.

Although there is a variety of animal models available, neither a single assay system nor the results of the various assays permit absolute protection of relative anti-inflammatory potency. Equally, current clinical dose titration studies, although more reliable, provide only gross estimates of therapeutic potency when conducted in certain clinical situations in a double-blind randomized fashion. This paper delineated clinical means to titrate more objectively and accurately therapeutic potency in the patient. Moreover, it has submitted considerations as to how to assess therapeutic anti-inflammatory activity in the complex multi-component process of inflammation accompanying most dermatologic diseases that eventually may permit titration of specific anti-inflammatory compounds on certain tissue components of the inflammatory process.

Administration, Topical↗
PubMed2000

[Rigorous algorithms for calculating the exact concentrations and activity levels of all the different species during acid-base titrations in water].

The principles of two algorithms allowing the calculations of the concentration and activity levels of the different species during acid-base titrations in water are described. They simulate titrations at constant and variable ionic strengths respectively. They are designed so acid and base strengths, their concentrations and the titrant volume added can be chosen freely. The calculations are based on rigorous equations with a general scope. They are sufficiently compact to be processed on pocket calculators. The algorithms can easily simulate pH-metric, spectrophotometric, conductometric and calorimetric titrations, and hence allow determining concentrations and some physico-chemical constants related to the occurring chemical systems.

Acid-Base Equilibrium↗
PubMed1975

Fluorometric determination of "albumin-titratable bilirubin" in the jaundiced neonate.

We report a fluorometric technique for determination of albumin-titratable bilirubin in the jaundiced neonate. Although bilirubin alone has very little native fluorescence, considerable emission is observed in the presence of albumin under acid conditions. Analysis of the plasma sample alone and in the presence of excess human serum albumin solution appears to reflect the bilirubin tightly bound to albumin and the total serum bilirubin, respectively. The difference between these two values has been designated as "albumin-titratable bilirubin". Where the concentration of albumin-titratable bilirubin is considerable, a typical saturation effect is observed. In samples where the circulating bilirubin is strongly bound to endogenous alumin, no change in fluorescence is seen when exogenous albumin is added. Results correlate well with the clinical picture.

Bilirubin↗
PubMedDate not supplied

Automatic flow system titration based on multicommutation for spectrophotometric determination of total acidity in silage extracts.

A multicommutated flow titration procedure is proposed for the spectrophotometric determination of total acidity in silage extracts. The flow network comprises a set of 3-way solenoid valves, computer-controlled to provide facilities to handle the titrand, titrant, and carrier solutions by using a single pumping channel. The procedure is based on the volumetric fraction variation approach that maintains the same volume of titrand solution and varies the titrant solution step by step, to provide determination without the use of an analytical curve. The procedure is implemented by using phenolphthalein as an external indicator; the proposed algorithm was able to titrate silage extracts presenting different color intensities. Sample solutions with concentrations ranging from 10(-3) to 10(-1) mol/L total acidity could be analyzed by using 10(-2) mol/L sodium hydroxide as the titrant solution. Other advantages include a relative standard deviation of <1.0% (n = 4) for a typical silage extract solution containing 26 mmol/L total acidity; an analytical throughput of 16 determinations per hour was also achieved. Accuracy was assessed by processing a set of silage extract solutions and comparing the results with those obtained by using the conventional potentiometric titration procedure. No significant difference at the 95% confidence level was observed.

Hydrogen-Ion Concentration↗
PubMed2003

Spectroscopic study on variations in illite surface properties after acid-base titration.

FT-IR, Raman microscopy, XRD, 29Si and 27Al MAS NMR, were used to investigate changes in surface properties of a natural illite sample after acid-base potentiometric titration. The characteristic XRD lines indicated the presence of surface Al-Si complexes, preferable to Al(OH)3 precipitates. In the microscopic Raman spectra, the vibration peaks of Si-O and Al-O bonds diminished as a result of treatment with acid, then increased after hydroxide back titration. The varied ratio of signal intensity between (IV)Al and (VI)Al species in 27Al MAS NMR spectra, together with the stable BET surface area after acidimetric titration, suggested that edge faces and basal planes in the layer structure of illite participated in dissolution of structural components. The combined spectroscopic evidence demonstrated that the reactions between illite surfaces and acid-leaching silicic acid and aluminum ions should be considered in the model description of surface acid-base properties of the aqueous illite.

Aluminum↗
PubMed2005

Reduction in use of healthcare services with combination sulfonylurea and rosiglitazone: findings from the Rosiglitazone Early vs SULfonylurea Titration (RESULT) study.

OBJECTIVE: To assess and compare healthcare utilization and costs over a 2-year period in older patients (> or = 60 years) with type 2 diabetes receiving combination therapy with rosiglitazone plus a sulfonylurea (glipizide) or progressive up-titration of glipizide monotherapy. STUDY DESIGN: Two-year, randomized, double-blind, parallel-group clinical trial. PATIENTS AND METHODS: Older type 2 diabetic patients initially receiving submaximal doses of a sulfonylurea were randomized to receive rosiglitazone plus glipizide (n = 115) or up-titrated glipizide monotherapy (n = 110). Information on patient self-reported healthcare utilization (hospitalizations, emergency department [ED] visits, physician office visits) was collected prospectively for the duration of the trial. National average healthcare costs per unit were applied to calculate direct medical costs. RESULTS: Demographic characteristics of the 2 groups were similar. At the study's end, glycemic values were better in the rosiglitazone-plus-glipizide group. Compared with the glipizide group, patients receiving rosiglitazone plus glipizide had significantly fewer ED visits (P = .0006) and hospitalizations (P = .0263). Although the glipizide group had more unscheduled physician office visits, the difference was not statistically significant. Estimated treatment costs per patient per month were significantly lower for the rosiglitazone-plus-glipizide group than for the glipizide group (480 dollars vs 645 dollars; P < .05). CONCLUSION: Addition of rosiglitazone to sulfonylurea therapy was associated with decreased use of medical resources, in particular hospitalizations and ED visits, compared with progressive sulfonylurea up-titration. Although causality could not be established, this therapeutic approach could improve clinical outcomes in patients with type 2 diabetes and reduce healthcare utilization and costs.

Adult↗
PubMed2005

[Changes in shape of upper airway during titrated mandibular advancement: a magnetic resonance imaging study].

OBJECTIVE: To examine adaptive changes in the shape of the upper airway during titrated mandibular advancement. Furthermore, to understand the mechanism of mandible-adjustable therapy to improve the ventilation. METHODS: Fourteen non-apnea participated in the study. A custom-made oral device was used to keep the mandible in titrated advancement at 0% (F0), 50% (F50), 75% (F75), 100% (F100) of the maximum advancement. Magnetic resonance imaging was used to investigate the difference in the shape of upper-airway in these 4 positions. Changes in the anteroposterior direction (AP), lateral direction (Lat) and its ratio (AP/Lat) were calculated, which were transformed into the percentage of the original ones. RESULTS: The dose-dependent decrease of AP/Lat was found when the mandible was advanced (P = 0.0001). Lateral change rate in percentage increased by degrees (P = 0.0023), while the increase of anteroposterior change rate in percentage showed no statistical significance. CONCLUSION: The shape of upper airway tended to be less round. The enlargement of upper airway during titrated mandibular advancement was mainly the result of enlargement in lateral direction.

Asian People↗
PubMed2006

The effect of cooking method upon the titratable acidity of a popular vegetarian dish--scope for reducing its erosive potential?

The purpose of this in vitro study was to determine the effect of cooking method on the erosive potential of ratatouille. Two cooking methods, stewing and oven roasting, were applied to standardised ingredients taken from the same fruits and vegetables. The resultant dishes were liquidised and diluted with 100 mls of distilled water. Five 25 ml samples of each group were titrated to pH 7.0 against 0.1 Molar Sodium Hydroxide. In order to ascertain the relative contribution of each ingredient each was singly prepared and cooked by stewing or oven roasting following the same quantities and dilutions as for the dish as a whole. 25 ml samples of these were titrated to pH 7.0 against 0.1 Molar Sodium Hydroxide. For ratatouille as a dish significantly (P < 0.0001) more alkali had to be added to the oven roast group (Mean = 8.60 mls, S.D. = 0.31) than to the stewed group (Mean = 3.92 mls, S.D. = 0.50) in order to bring about neutrality. Oven roasting of ingredients significantly (P < 0.001) lowered the initial pH with the exceptions of tomatoes and red peppers. Stewing reduced the volume of alkali required to neutralise aubergine (P < 0.001), green peppers (P < 0.001) and courgettes (P < 0.05). Significantly (P < 0.001) more alkali however was required to neutralise stewed red pepper. It was concluded that the method of cooking identical ingredients affects the erosive potential of ratatouille. Although oven roasting results in a higher erosive potential of ratatouille compared to stewing the method of cooking, at an individual ingredient level, does not have a universal effect upon erosive potential as determined by titratable acidity. This should be borne in mind when advising patients.

Acids↗
PubMed2006

Application of highly accurate nephelometric titration in the assaying of phenytoin sodium.

AIM: To determine phenytoin sodium by a highly accurate nephelometric titration. METHODS: The titration operating conditions were optimized and the solubility product constant of phenytoin silver precipitation was determined. RESULTS: The result of the titration is comparable to those of control experiments. CONCLUSION: The proposed method has been found to be accurate, precise, specific, reproducible, and linear.

Nephelometry and Turbidimetry↗
PubMed1976

Routine titration of foot and mouth disease virus suspensions by analytical ultracentrifugation. 1: Sedimentation method.

Infectivity and Complement Fixation (CF) tests are commonly used for the routine titration of Foot and Mouth Disease (FMD) virus suspensions. Only recently were techniques published for the routine determination of the virus concentration by the physical properties of the virions (Fayet et al., 1971; Barteling et al., 1974). These techniques are based on the separation of the virions from the culture fluid by sedimentation through a sucrose gradient, in a preparative ultracentrifuge. The ultraviolet absorption pattern of the tube content is recorded by a flow colorimeter. The virus concentration is estimated using either standard curves or direct caculation by the specific extinction coefficient (Bachrach et al., 1964). In our own attempts to develop a preparative ultracentrifugation technique for the routine titration of FMD virus suspensions, we had to deal with some problems such as remixing of the virus band at the end of the run. We therefore turned over to analytical ultracentrifugation methods. The manipulations are less complicated and the virus band is traced and measured while the rotor is spinning. Four samples are analyzed simultaneously and the scans are repeated to follow the move of the virus band. The sedimentation rate of the virus band, calculated from the repeated scans, helps to detect artifacts. The present paper describes the technique we developed for the routine titration of FMD virus suspensions, by the band sedimentation method, using an ultraviolet scanning analytical ultracentrifuge.

Aphthovirus↗
PubMed1990

Thermodynamic properties of the binding of alpha-, omega-amino acids to the isolated kringle 4 region of human plasminogen as determined by high sensitivity titration calorimetry.

The binding of alpha-, omega-amino acids, which are important effectors of human plasminogen activation, to the isolated kringle 4 (K4) peptide region of this protein has been investigated by high sensitivity titration calorimetry. The titration curve of the heat changes accompanying binding of the widely employed ligand, epsilon-aminocaproic acid (EACA), to K4 were deconvoluted to yield the following binding characteristics: n = 0.87 +/- 0.08 mol/mol; Ka = 3.82 +/- 0.37 x 10(4) M-1; delta H = -4.50 +/- 0.22 kcal/mol; delta S = 6.01 +/- 0.7 entropy units; and delta G = 6.29 +/- 0.06 kcal/mol. Here, both delta H and delta S provide the driving force of the interaction, with both hydrogen bonds and hydrophobic interactions, the latter which may result from an induced conformational change in K4 upon ligand binding, as well as possible alterations in peptide-bound water structure, providing the stabilizing forces for complex formation. The thermodynamic binding parameters were not greatly influenced by pH between the values of 5.5 and 8.2, suggesting that titratable groups on K4 in this pH region did not influence the binding. Investigations of the binding properties of structural analogues of EACA to K4 demonstrated that definable steric requirements existed for a maximal interaction, with spacing between the functional groups on EACA, as well as a hydrophobic region of this molecule, being important. This rapid and reliable method for measuring all thermodynamic parameters of formation of this complex at a given temperature can now be employed to investigate this important interaction with a wide variety of kringles and modified kringles to provide a more complete understanding of the necessary factors for this binding to occur.

Amino Acid Sequence↗
PubMedDate not supplied

Rapid and precise whole blood protamine titration.

A rapid and precise whole blood protamine titration method was developed. The method uses azure A dye as the titration indicator and thereby replaces the tedious and time-consuming clotting assay with a facile colorimetric assay. The method provides the same accuracy in estimating the titration end-point, but allows the processing time to be shortened to that required by current clinical methods. The simplicity, flexibility, speed, and accuracy offered by the method, and the ability to use whole blood specimens for the measurements, should allow the method to be used by clinicians in the operating room or during a surgical procedure to estimate the adequate protamine dose required for heparin reversal.

Azure Stains↗
PubMed1990

[Kalman filtering-titrimetry: potentiometric titration of benzalkonium bromide].

The application of Kalman filtering and smoothing to titrimetry has been investigated. The method is suitable for titration systems in both thermodynamic equilibrium and non-equilibrium (dynamic). Particularly, Kalman filtering and smoothing can give correct results in cases when other traditional methods failed. The effect of model noise, titration rate and sampling time was also examined on the accuracy of the filtering titrimetry. The proposed method has been applied to potentiometric titration and rapid determination of benzalkonium bromide.

Benzalkonium Compounds↗
PubMed1989

Spectrophotometric and spectrofluorometric titrations of teichoic acid.

Spectrophotometric and spectrofluorometric titrations of two strongly aggregating dyes, 1,9-dimethylmethylene blue (DMMB) and acridine orange (AO), by three anionic biopolymers, chondroitin sulphate A, DNA and teichoic acid (TA), have been described. Though the three polymers differ in their dye binding efficiencies and TA is a weak chromotrope, the equivalent weights of the polymers can be estimated accurately by these methods using the two dyes. Results show DMMB to be the preferred dye for spectrophotometric titration. The titrations can be used to estimate the equivalent weights of anionic polymers, and also for the quantitative estimation of such polymers of known equivalent weights.

Acridine Orange↗
PubMed1989

The molecular mechanism of the neutral-to-base transition of human serum albumin. Acid/base titration and proton nuclear magnetic resonance studies on a large peptic and a large tryptic fragment of albumin.

In order to obtain a better understanding of the neutral-to-base (N-B) transition of human serum albumin, we performed acid/base titration experiments and 500-MHz 1H NMR experiments on albumin and on a large peptic (residues 1-387) and large tryptic (residues 198-585) fragment of albumin. The acid/base titration experiments revealed that Ca2+ ions induce a downward pK shift of several histidine residues of the peptic (P46) fragment and of albumin. By contrast, Ca2+ has very little influence on the pK of histidine residues of the tryptic (T45) fragment. In albumin, the pH-dependent His C-2 proton resonances, observed with 1H NMR experiments, have been allotted the numbers 1-17. It proved possible to locate these resonances in the P46 and the T45 fragments. A correspondence was found between the number of histidines detected by the acid/base titration and by the 1H NMR experiments. The results of the experiments lead us to conclude that in domain 1 at least the histidines corresponding to the His C-2 proton resonances 1-5 play a dominant role in the N-B transition. The Cu2+-binding histidine residue 3 (resonance 8) of the albumin molecule is not involved in the N-B transition. In addition, we were able to assign His C-2 proton resonance 9 to histidine 464 of the albumin molecule. The role of the N-B transition in the transport and cellular uptake mechanisms of endogenous and exogenous compounds is discussed.

Binding Sites↗
PubMed1987

[Titration curves of beta-lactamases using pH gradient electrophoresis].

The molecular relationships of two types of plasmid-mediated beta-lactamases, TEM-1 (R 111), TEM-2 (RP 4) and OXA-1 (RGN 238), OXA-4 (pMG 90) were analysed by combined isoelectrofocusing-electrophoresis. Titration curves of TEM-1 (pI 5.4) and TEM-2 (pI 5.6) together were consistent with the known substitution of a glutamic acid in the former by a lysin in the latter. When OXA-1 (pI 7.4) and OXA-4 (pI 7.45) were titrated, one single mobility curve was obtained reflecting their structural homogeneity. The titration curve technique will be usefull for the study of structure of beta-lactamases.

Electrophoresis, Polyacrylamide Gel↗
PubMed1988

Conformationally restricted analogs of angiotensin II: titration and biological activity.

1. Six conformationally restricted analogues of angiotensin II containing one disulfide bridge were synthesized by the solid-phase method. 2. These cyclic analogues were titrated electrometrically and spectrophotometrically and their biological activities were assayed on the isolated guinea pig ileum and rat blood pressure. 3. The conformation restrictions led to significant differences in the pKa values of the titratable groups in all six analogs. 4. The comparison of titration data between the cyclic and linear analogs of angiotensin II indicates that in the pH range 4 to 9, angiotensin II has a preferential folded conformation. An expanded conformation is assumed to occur at pH below 4 and above 9. 5. The biological activities of all cyclic analogs were less than 0.2% of the activity of angiotensin II in both bioassays.

Amino Acid Sequence↗
PubMed1979

A comparison by 220-MHz NMR of histidine hydronium ion titrations in porcine pancreatic ribonuclease and an extensively deglycosylated derivative.

220-MHz NMR was used to observe the titration behavior of the 5 histidine residues in porcine pancreatic ribonuclease (ribonucleate pyrimidine-nucleotido-2'-transferase (cyclizing), EC 3.1.4.22) and a derivative prepared by removal of 80% of the attached carbohydrate from this glycoprotein. Resonances due to histidine C-2 protons were observed over the full pH range for 3 of the residues; such resonances for the remaining 2 histidine residues broadened out as the pH was increased. Resonances due to histidine C-4 protons were also observed for 2 of the residues. The titration curves for both proteins were identical within experimental error. Resonances were assigned by comparison with histidine NMR titrations in ribonucleases from other species. Histidine 105, immediately adjacent to the site of attachment of a heterosaccharide side chain, has a C-2 proton chemical shift and pK that are insensitive to the large alteration in the bulk of the carbohydrate side chain. The chemical shifts of the C-2 proton of histidine 48 and of the C-4 proton of histidine 80, histidine residues that are close to one another and to another heterosaccharide side chain, show a similar insensitivity. The observations are direct evidence in support of the thesis that the heterosaccharides in porcine ribonuclease project away from the surface of the protein into the solution environment.

Animals↗