Development of retention mechanism for the separation of carboxylic acids and inorganic anions in cryptand-based ion chromatography.

The ion-exchange and complex forming equilibria were quantitatively described and demonstrated in order to understand major factors in the control of selectivity in the analytical separation of carboxylic acids and inorganic anions in cryptand based ion chromatography. A complex retention model has been developed for the separation on a non-conventional IC column. Changes in retention are treated both theoretically and experimentally. Retention mechanism is employed on a macrocycle-based (cryptand n-decyl-[2.2.2]) ion-exchange chromatographic phase to improve the selectivity for a mixture of model analytes. We introduced an alternative internal gradient method by mixed eluent (i.e. eluents formed by combination of two alkali hydroxide with different molar ratio). The effect of binary mixed eluent (Li/Na, Li/K) on the retention behavior and peak shape of carboxylic acids are also discussed in view of the proposed theory. It was shown that the effects of binary aqueous mobile phases, held isocratically behave very similar to the step gradient mode. The "internal gradient" separation system has advantages over traditional step gradient mode. Twenty-six anions of widely varying chemical character (mono-, di-, tri-valent inorganic anions, mono-, di-, tri-valent aliphatic carboxylic acids, aromatic- and haloacetic carboxylic acids) were investigated on the cryptand-based (D222) stationary phase using different methods by LiOH, NaOH and KOH eluent. The predicted vs measured retention data are in rather good agreement. High degree of linearity was obtained for inorganic anions, multivalent carboxylic acids, and for aromatic and haloacetic acids R2 = 0.992, 0.969, and 0.980, respectively.

[Glucagon-like peptide-1 (GLP1) and the gastrointestinal tract. GLP1 receptor agonists: overemphasized gastric, forgotten intestinal ("ileal brake") effect?] / A glükagonszeru peptid-1 (GLP1) és a gyomor-bél rendszer. GLP1-receptor-agonisták ­ túlértékelt gyomor-, elfelejtodött bél- ("ileal brake") hatás?

Glucagon-like peptide-1 (GLP1) and their receptor agonists - beside their blood glucose lowering and central effects- affect also the gastrointestinal function in many respects. They slow down the stomach emptying, the motility of the small bowel and colon - this is the explanation for the "ileal brake" terminology -, stimulate the function of exocrine pancreatic acinar cells and increase amylase production. GLP1 receptor agonists belong to the defining tools of the blood glucose lowering therapy in type 2 diabetes. Their long- and short-acting derivatives have different influence on the fasting and the postprandial blood glucose, respectively. By introducing the term non-prandial and prandial type analogues - which seems to be forced in light of the newer data - the potential slowdown in gastric emptying is the center of interest, lately, however, especially in the case of long-acting GLP1 variants, at least such attention should be paid to controlling bowel function. The article reviews the physiological effects of GLP1 on the gastrointestinal tract and draws attention to the potential for the prevention of possible side effects through detailed patient information and dietary advises. Orv Hetil. 2019; 160(49): 1927-1934.

High Performance Anion Chromatography of Gadolinium Chelates.

High performance anion chromatography (HPIC) method to separate ionic Gd chelates, [Formula: see text], [Formula: see text], [Formula: see text] and free matrix anions was developed. At alkaline pHs, polydentate complexing agents such as ethylene-diamine-tetraacetate, diethylene-triamine pentaacetate and trans-1,2-diamine-cyclohexane-tetraacetate tend to form stable Gd chelate anions and can be separated by anion exchange. Separations were studied in the simple isocratic chromatographic run over the wide range of pH and concentration of carbonate eluent using suppressed conductivity detection. The ion exchange and complex forming equilibria were quantitatively described and demonstrated in order to understand major factors in the control of selectivity of Gd chelates. Parameters of optimized resolution between concurrent ions were presented on a 3D resolution surface. The applicability of the developed method is represented by the simultaneous analysis of Gd chelates and organic/inorganic anions. Inductively coupled plasma atomic emission spectroscopy  (ICP-AES) analysis was used for confirmation of HPIC results for Gd. Collection protocols for the heart-cutting procedure of chromatograms were applied. SPE procedures were also developed not only to extract traces of free gadolinium ions from samples, but also to remove the high level of interfering anions of the complex matrices. The limit of detection, the recoverability and the linearity of the method were also presented.

Solvent minimization in two-dimensional liquid chromatography.

An algorithm was developed for the minimization of consumption of organic solvent in comprehensive two-dimensional liquid chromatography (2DLC). It was shown that one can reach higher peak capacities only by using more eluent. The equilibration volume of the second dimension, however, did not affect the solvent consumption significantly. Calculations confirmed that the same target peak capacity could be achieved by consuming significantly different volume of organic modifier depending on the number of fractions analyzed in the second dimension suggesting that 2D separations can be optimized for eluent consumption. It was shown that minimization of eluent usage requires the use of small and high efficient columns in the second dimension. A simple equation was derived for the calculation of the optimal number of collected fractions from the first dimension that allowed the minimization of eluent usage, cost and environmental impact of comprehensive 2DLC separations.

TiO2-Mediated Photocatalytic Mineralization of a Non-Ionic Detergent: Comparison and Combination with Other Advanced Oxidation Procedures.

Triton X-100 is one of the most widely-applied man-made non-ionic surfactants. This detergent can hardly be degraded by biological treatment. Hence, a more efficient degradation method is indispensable for the total mineralization of this pollutant. Application of heterogeneous photocatalysis based on a TiO2 suspension is a possible solution. Its efficiency may be improved by the addition of various reagents. We have thoroughly examined the photocatalytic degradation of Triton X-100 under various circumstances. For comparison, the efficiencies of ozonation and treatment with peroxydisulfate were also determined under the same conditions. Besides, the combination of these advanced oxidation procedures (AOPs) were also studied. The mineralization of this surfactant was monitored by following the TOC and pH values, as well as the absorption and emission spectra of the reaction mixture. An ultra-high-performance liquid chromatography (UHPLC) method was developed and optimized for monitoring the degradation of Triton X-100. Intermediates were also detected by GC-MS analysis and followed during the photocatalysis, contributing to the elucidation of the degradation mechanism. This non-ionic surfactant could be efficiently degraded by TiO2-mediated heterogeneous photocatalysis. However, surprisingly, its combination with the AOPs applied in this study did not enhance the rate of the mineralization. Moreover, the presence of persulfate hindered the photocatalytic degradation.

[De Quervain thyroiditis. Corner points of the diagnosis]. / A szubakut de Quervain-thyreoiditis. A kórismézés sarokpontjai négy eset kapcsán.

Inflammatory disorders of the thyroid gland are divided into three groups according to their duration (acute, subacute and chronic). De Quervain's thyroiditis (also termed giant cell or granulomatous thyroiditis) is a subacute inflammation of the thyroid, which accounts for 5% of thyroid disorders. The etiology is unknown, it usually appears two weeks after an upper viral respiratory infection. The clinical feature includes neck pain, which is aggravated during swallowing, and radiates to the ear. On palpation, the thyroid is exquisitely tender. The erythrocyte sedimentation rate is markedly elevated, the leukocyte count, C-reactive protein are normal or slightly elevated. The natural history of granulomatous thyroiditis involves four phases: the destructive inflammation results temporarily in hyperthyroidism followed by euthyroidism. After a transient hypothyroidism the disease becomes inactive and the thyroid function is normalised. Ultrasonographic findings are diffuse hypoechogenic structures, but nodules may also occur. The disease often remains unrecognised, or the first phase of the disease is diagnosed and treated as hyperthyroidism. The diagnosis can be confirmed by the presence of the thyroid autoantibodies, radioiodine uptake and fine needle aspiration cytology. There is no special treatment, non-steroid anti-inflammatory drugs or steroid should be given to relieve the pain. The aim of the authors is to shed light the key points of diagnosis and differential diagnosis by the presentation of four slightly different cases.

Degradation of industrial surfactants by photocatalysis combined with ozonation.

The efficiency of titanium dioxide-mediated photocatalytic degradation of pollutants can be enhanced by combination with another advanced oxidation procedure such as ozonation. Mineralization of hydroxy- and dihydroxybenzenesulfonate based on these methods, both individually and combined, was investigated by monitoring the total organic carbon content, sulfate concentration, pH, high-performance liquid chromatography as well as the absorption spectral changes. The mineralization efficiency of the combined procedure significantly exceeded the sum of those of the individual techniques. The comparison of the disappearance of the starting material and the formation of the sulfate ions indicates that desulfonation is not the primary step of the degradation. Moreover, in the case of the combined method, ring cleavage, and thus, partial mineralization can occur without desulfonation. Efficient degradation of other, widely used industrial surfactants, such as alkylbenzene sulfonates and alkyl ether sulfates, was also achieved by heterogeneous photocatalysis combined with ozonation, offering an applicable method for the removal of these pollutants.

High performance ion chromatography of transition metal chelate complexes and aminopolycarboxylate ligands.

A simple ion chromatographic method was developed for the separation of transition metal chelates (CuEDTA, CuDCTA, ZnEDTA, ZnDCTA) and free anionic complexing ligands (EDTA, DCTA) using alkaline carbonate eluents and conductivity detection. The complex equilibria and kinetic process of separations were studied in order to understand major factors in the control of selectivity and retention order of complex anions. A systematic study was applied to identify the additional peaks of the system as NaEDTA(3-), NaHEDTA(2-), Na(2)EDTA(2-), EDTA(4-)/HEDTA(3-), DCTA(4-)/HDCTA(-3). On the basis of microequilibrium considerations of chelating ligand, it was shown that one should expect the peaks of sodium chelates when the ligand is in excess in the sample solution. The probability density function was introduced for calculation of complex chromatograms, because complexing ligands can exist in at least two different interconvertible forms in the presence of metal ion. The chromatogram of interconverting chelate species can be given as the sum of probability density functions (P) weighed by the molar fractions of complexed (Φ(ML)) and dissociated (Φ(L)) forms. The influences of kinetic rate of complex formation and dissociation on the distribution of components between eluents and ion exchange stationary phases were quantitatively described and demonstrated by elution profiles. The applicability of the developed method is represented by the simultaneous analysis of transition metal chelates and inorganic anions. ICP-AES analysis and FTIR-ATR technique were used for confirmation of IC results for metals and ligands, respectively. Collection protocols for the heart-cutting procedure of chromatograms were applied in the analysis of target components. The limit of detection and linearity of the method in the range of 0.01-0.25 mM sample concentration were also presented.

[Verrucous carcinoma of the anal margin. The importance of adequate biopsy technique]. / Verrucosus analis carcinoma (Buschke-Löwenstein-tumor): a körültekinto biopsziás mintavétel jelentosége.

Buschke-Löwenstein tumor (verrucous carcinoma, giant condylomata) of the anal margin is a locally invasive, destructively growing carcinoma that does not metastasize. The lesions are rare despite the increased incidence of anal condylomata and anal carcinomas. Authors report a case of a 63-year-old woman suffering from verrucous carcinoma (Buschke-Löwenstein tumor) of the anal margin. The tumor invaded the rectal sphincter and extended beyond the muscle, infiltrating the lower abdomen. Infiltration of the perivesical soft tissue caused bilateral hydronephros. Because both under- and overdiagnosis of anal cancer and precancer may lead to inappropriate treatment, it is important to perform adequate sampling for histology. Non-representative superficial biopsies may result underdiagnosis of the disease.

Boronic acid lectin affinity chromatography (BLAC). 3. Temperature dependence of glycoprotein isolation and enrichment.

In this paper, the effect of temperature is investigated on the performance of glycoprotein enrichment by boronic acid lectin affinity chromatography (BLAC). Wheat germ agglutinin and m-aminophenyl boronic acid containing stationary phases were evaluated individually and in a mixed mode using an automated liquid handling robot with an integrated 96-well plate temperature controller. Glycoaffinity enrichment of the model proteins of ribonuclease B and trypsin inhibitor was investigated in the presence of the non-glycosylated proteins of myoglobin (neutral) and lysozyme (basic) at a wide temperature range of 5-65 degrees C. Our results revealed that glycoaffinity micropartitioning at the temperature of 25 degrees C provided the highest recovery rate for glycoprotein enrichment. We have also found that a large amount of lysozyme was present in the elution fractions of the m-aminophenyl boronic acid containing micropartitioning columns due to ion-exchange mechanism occurring between the positively charged protein and the negatively charged stationary phase at the operation pH. On the other hand, at high temperature (65 degrees C), non-specific interactions with the agarose carrier prevailed, evidenced by the presence of myoglobin in the eluate.

Equilibrium-based approach for prediction of matrix-related interferences in anion chromatography.

The retention behavior of low-concentration inorganic anions was studied systematically as a function of changing high matrix anion concentration. Stoichiometric retention model was developed for interpretation and prediction of matrix effects in ion chromatography. The model was tested and utilized for separation of low concentration (1-5 mg/l) bromate, bromide, chloride, nitrate, ethanesulfonate, and pentanesulfonate ions with carbonate buffer and hydroxide eluent in relatively wide ranges of sulfate matrix (>2000 mg/l). Equilibrium-based approach effectively characterizes the selectivity of the complex system through differences in ion-exchange constants of analyte, eluent and matrix ions. Selectivity data were determined from the experimental retention data by iterative calculations using the derived equations. The predicted and observed retention data are in rather good agreement. The method describes precisely the retention shift of trace anions in the high level of ionic matrices. The results in quantitative three-dimensional retention surfaces (k, matrix and eluent concentration) together with species distribution graphs are also presented.

Sample preparation for the analysis of complex carbohydrates by multicapillary gel electrophoresis with light-emitting diode induced fluorescence detection.

This paper evaluates various sample preparation methods for multicapillary gel electrophoresis based glycan analysis to support electrokinetic injection. First the removal of excess derivatization reagent is discussed. Although the Sephadex G10 filled multiscreen 96-well filter plate and Sephadex G10 filled pipet tips enabled increased analysis sensitivity, polyamide DPA-6S pipet tips worked particularly well. In this latter case an automated liquid handling system was used to increase purification throughput, necessary to feed the multicapillary electrophoresis unit. Problems associated with the high glucose content of such biological samples as normal human plasma were solved by applying ultrafiltration. Finally, a volatile buffer system was developed for exoglycosidase-based carbohydrate analysis.

High performance ion chromatography of haloacetic acids on macrocyclic cryptand anion exchanger.

A new high performance ion chromatographic method has been developed for the separation of the nine chlorinated-brominated haloacetic acids (HAAs) that are the disinfection by-products of chlorination of drinking water, using a macrocycle-based adjustable-capacity anion-exchange separator column (IonPac Cryptand A1). A gradient method based on theoretical and experimental considerations has been optimized in which 10 mM NaOH-LiOH step gradient was performed at the third minute of the analysis. The optimized method allowed us to separate the nine HAAs and seven possibly interfering inorganic anions in less than 25 min with acceptable resolution. The minimum concentrations detectable for HAAs were between 8.0 (MBA) and 210 (TBA) microg L(-1), with linearity included between 0.9947 (TBA) and 0.9998 (MBA). To increase sensitivity, a 25-fold preconcentration step on a reversed phase substrate (LiChrolut EN) has been coupled. Application of this method to the analysis of haloacetic acids in real tap water samples is illustrated.

Retention controlling and peak shape simulation in anion chromatography using multiple equilibrium model and stochastic theory.

The stochastic theory of chromatography and an equilibrium based approach were used for the prediction of peak shape and retention data of anions. This attempt incorporating the potential advantages of two different chromatographic phenomena for analytical purposes. It is an integrated method to estimate kinetic and thermodynamic properties for the same chromatographic run of ions. The stochastic parameters of eluted anions, such as the residence time of the molecule on the surface of the stationary phase, and the average number of adsorption steps were determined on the basis of a retention database of organic and inorganic anions (formate, chloride, bromide, nitrate, sulphate, oxalate, phosphate) obtained by using carbonate/bicarbonate eluent system at different pHs (9-11) and concentrations (7-13 mM). In the investigated IC system the residence times are much higher and the average number of sorption steps is somewhat smaller than in RP-HPLC. The simultaneous application of the stochastic and the multispecies eluent/analyte model was utilized to peak shape simulation and the retention controlling of various anions under elution conditions of practical importance. The similarities between the measured and the calculated chromatograms indicates the predictive and simulation power of the combined application of the stochastic theory and the multiple species eluent/analyte retention model.

Retention profiles and mechanism of anion separation on latex-based pellicular ion exchanger in ion chromatography.

A retention model based on stoichiometric approach has been developed in order to describe analyte retention of anions on latex-based pellicular ion exchanger. The chromatographic process entails two stepwise and complex equilibria, first is ion-pair forming of analyte or eluent ion with ion-exchange sites under the effect of electrostatic forces due to the sulfonic layer behind the aminated functional groups of stationary phase. Second component is the ion-exchange between the analyte and eluent ions. As a new parameter of the fractional electrostatic coefficient of the ion exchange capacity was introduced to develop retention profiles of anions. Analysis of the dependence of the capacity factors on the eluent concentrations at different values of fractional coefficient shed light on the possible complex mechanism. Extensive experimental retention data were obtained for 14 anions (formate, acetate, propionate, pyruvate, lactate, chloride, nitrate, oxalate, malonate, succinate, tartarate, fumarate, maleate, sulphate) using hydroxide eluents of varying concentration. The ion-pair formation and ion-exchange selectivity constants for analyte and eluent species are determined using derived retention equation from experimental data by nonlinear iterative calculation. The model was utilized to predict retention data under elution conditions of practical importance. The predicted and obtained retention factors are in good agreement, which confirms the predictive power of the model.

Ethylenediamine as eluent component in cation chromatography. Predictive and comparative study for analysis of alkaline earth ions.

The retention behaviour of alkaline earth cations was studied as a function of changing composition of acidified ethylenediamine eluent. The multiple eluent species retention model developed for separation of calcium, magnesium and strontium ions was utilized for determination of selectivity coefficients for sample and eluent ions. The suggested model accurately describes and predicts retention of analytes under elution conditions [0.5-2.0 mM C2H4(NH2)2 and pH 4-6] which are of practical importance. The results in three-dimensional retention surface with species distribution graphs are demonstrated. Complexometric titrations and ion chromatography (IC) were compared for the analysis of calcium and magnesium ions. Statistical data indicated that there was no evidence for relative differences between the two methods. However, IC gives several advantages over volumetric method.

Tumor necrosis factor system in insulin resistance in gestational diabetes.

OBJECTIVE: The aim of the study was to investigate the pathophysiological role of the tumor necrosis factor (TNF) system in insulin resistance in patients with gestational diabetes (GDM) and during the course of normal pregnancy. PATIENTS AND METHODS: Thirty women with GDM (16-39 gestational weeks), 35 healthy pregnant women (15 first, nine second and 11 third trimester) and 25 healthy age-matched non-pregnant women were studied. Serum TNF-alpha, and its soluble receptors 1 and 2 (sTNFR-1 and -2) were measured. RESULTS: In non-diabetic pregnant women in the third trimester all measures were significantly higher (P<0.05 or less) than in the first trimester and in non-pregnant women (BMI 27.6 +/- 4.1 (+/- S.D.), 24.1 +/- 2.6, 22.4 +/- 2.4 kg/m(2)), serum TNF-alpha (4.6 +/- 0.6, 4.1 +/- 0.4, 4.1 +/- 0.4 ng/l), sTNFR-1 (2.7 +/- 0.9, 2.0 +/- 0.5, 2.0 +/- 0.1 microg/l), sTNFR-2 (5.6 +/- 2.6, 4.6 +/- 2.1, 3.3 +/- 0.2 microg/l), C-peptide (3.1 +/- 1.7, 1.1 +/- 0.7, 1.1 +/- 0.8 microg/l), and C-peptide:blood glucose ratio (0.6 +/- 0.2, 0.2 +/- 0.1, 0.2 +/- 0.1 microg/mmol). In GDM these measures were even higher than in any subgroup of healthy pregnant women (BMI) (33.4 +/- 6.4 kg/m(2), TNF-alpha) (6.3 +/- 0.6 microg/l), sTNFR-1 (3.0 +/- 0.5 microg/l), sTNFR-2 (10.0 +/- 6.9 microg/l, C-peptide 6.0 +/- 2.7 microg/l, C-peptide:blood glucose ratio: 1.2 +/- 0.5 microg/mmol, P<0.01). Significant (P<0.01) positive linear correlations were found in gestational diabetic and non-diabetic women between serum TNF-alpha, C-peptide levels, and BMI. In gestational diabetic women, in multivariate analysis studying the dependency of C-peptide only BMI remained significant (r(2)=0.67, P=0.01). CONCLUSIONS: Our observation emphasizes the obesity-related component of insulin resistance driven by adipocytokines, such as TNF-alpha and its receptors during the course of normal pregnancy and GDM.