Correlation between biochemical features and outcomes of preoperative imaging (SPECT-CT and Ultrasound) in primary hyperparathyroidism.

Background: Primary hyperparathyroidism is the third most common endocrine disorder, diagnosed by elevated parathyroid hormone (PTH) in hypercalcaemia. Several biochemical factors have been described to suggest severity of disease and may be correlated with preoperative imaging. Methods: This was a retrospective study of patients who underwent parathyroidectomy over a 3-year period. Preoperative calcium, PTH, vitamin D levels, ALP (alkaline phosphatase), vitamin D, serum phosphate and US and SPECT-CT positivity was noted. Results: 176 patients underwent parathyroidectomy and these were divided into 4 groups based on preoperative calcium. Overall, 61% of patients showed concordance between imaging and operative findings. Severe hypercalcaemia was associated with higher PTH levels, lower vitamin D levels, an increased rate of abnormal ALP levels, lower phosphate, male gender and highest rate of imaging concordance. Imaging positivity was associated with severe hypercalcaemia and elevated PTH levels. Level of PTH >125 pmol/L and hypercalcaemia >2.8 mmol/L are the most accurate cut-off levels for scan positivity. Conclusion: Biochemical factors associated with severity of the disease are directly correlated with positivity of preoperative imaging while ALP and vitamin D did not influence the preoperative imaging positivity but are associated with disease adversity. Serum phosphate level independently predicted results of parathyroid US.

Changing pattern of pheochromocytoma and paraganglioma in a stable UK population.

CONTEXT: Pheochromocytomas and paragangliomas (PCC/PGLs) are diagnosed variously with increasing incidence and changing clinical and pathology pattern. OBJECTIVE: The aim was to further characterize PCC/PGLs in a stable population. METHODS: A retrospective, single institution study analysed adrenalectomies for PCC/PGLs between January 2010 - January 2019. Demographics, symptoms, blood pressure, preoperative hormones, imaging, histology, hospital stay, complications and three subgroups [based on the modality of diagnosis - incidentaloma group (IG), genetic group (GG) and symptomatic group (SG)] were noted. RESULTS: 86 patients included IG 51 (59.3%), GG 10 (11.62%) and SG 25 patients (29.06%). Incidence was 5.30 cases/1 million population. 33.34% of the IG had a delayed diagnosis with a mean interval of 22.95 months (4-120 months). Females presented more often with paroxysmal symptoms (PS) (p=0.011). Patients with PS and classic symptoms were younger (p=0.0087, p=0.0004) and those with PS required more inotropes postoperatively (p=0.014). SG had higher preoperative hormone levels (p=0.0048), larger tumors (p=0.0169) and more likely females. GG are younger compared with those from the IG (p=0.0001) or SG (p= 0.178). CONCLUSION: Majority of patients had an incidental and delayed diagnosis. If symptomatic, patients are more likely to be young females with higher hormone levels and larger tumors.

Study of nucleic acid-ligand interactions by capillary electrophoretic techniques: A review.

The understanding of nucleic acids-ligand (proteins, nucleic acids or various xenobiotics) interactions is of fundamental value, representing the basis of complex mechanisms that govern life. The development of improved therapeutic strategies, as well as the much expected breakthroughs in case of currently untreatable diseases often relies on the elucidation of such biomolecular interactions. Capillary electrophoresis (CE) is becoming an indispensable analytical tool in this field of study due to its high versatility, ease of method development, high separation efficiency, but most importantly due to its low sample and buffer volume requirements. Most often the availability of the compounds of interest is severely limited either by the complexity of the purification procedures or by the cost of their synthesis. Several reviews covering the investigation of protein-protein and protein-xenobiotics interactions by CE have been published in the recent literature; however none of them promotes the use of these techniques in the study of nucleic acid interactions. Therefore, various CE techniques applicable for such interaction studies are discussed in detail in the present review. The paper points out the particular features of these techniques with respect the estimation of the binding parameters, in analytical signal acquisition and data processing, as well as their current shortcomings and limitations.

Application of a new optimization strategy for the separation of tertiary alkaloids extracted from Strychnos usambarensis leaves.

The HPLC separation of six alkaloids extracted from Strychnos usambarensis leaves has been developed and optimized by means of a powerful methodology for modelling chromatographic responses, based on three steps, i.e. design of experiments (DoE), independent component analysis (ICA) and design space (DS). This study was the first application of a new optimization strategy to a complex natural matrix. The compounds separated are the isomers isostrychnopentamine and strychnopentamine, 10-hydroxyusambarine and 11-hydroxyusambarine, also strychnophylline and strychnofoline. Three LC parameters have been optimized using a multifactorial design comprising 29 experiments that includes 2 center point replicates. The parameters were the percentage of organic modifiers used at the beginning of a gradient profile which consisted in different proportions of methanol (MeOH) and acetonitrile (MeCN), the gradient time to reach 70% of organic modifiers starting from the initial percentage and the percentage of MeCN found in the mobile phase. Subsequent to the experimental design application, predictive multilinear models were developed and used in order to provide optimal analytical conditions. The optimum assay conditions were: methanol/acetonitrile-sodium pentane sulfonate (pH 2.2; 7.5 mM) (33.4:66.6, v/v) at a mobile phase flow rate of 1 ml/min during a 40.6 min gradient time. The initial organic phase contained 3.7% MeCN and 96.3% MeOH. The method showed good agreement between the experimental data and predictive value throughout the studied parameters space. Improvement of the analysis time and optimized separation for the compounds of interest was possible due to the original and powerful tools applied. Finally, this study permitted the acquisition of isomers profiles allowing the identification of the optimal collecting period of S. usambarensis.

Chemical composition of the essential oil of Salvia officinalis L. from Romania.

UNLABELLED: The quantitative and qualitative analysis of essential oils obtained from Salvia officinalis L. (Lamiaceae) cultivated in Romania is reported in this paper. MATERIAL AND METHODS: The essential oils were obtained from fresh and dried material harvested from plants cultivated in Cluj (Romania) and from 2 commercial samples, by hydrodistillation. The essential oils were analysed by GS-MS. RESULTS: 12 compounds were found in each oil, 9 of them being common in all samples. The alpha-thujone was the major compound in all analysed oils (31.23-52.86%), followed by camphor and viridiflorol. Chemically, the oxygenated monoterpenes are present in highest quantity (49.78-79.2%). CONCLUSIONS: The monoterpenoid ketones' presence (á-thujone, â-thujone, camphor) in high amounts in the essential oils of Romanian sage may develop toxicity for these products and may limit their medicinal use.

Fast determination of colchicine by TLC-densitometry from pharmaceuticals and vegetal extracts.

Colchicine, (S)-N-(5,6,7,9-tetrahydro-1,2,3,10-tetramethoxy-9-oxobenzo-(a(-heptalen-7-yl)-acetamide, is the main alkaloid contained in Colchicum autumnale (meadow saffron). There are known colorimetric, spectrophotometric, volumetric, potentiometric, voltametric, gravimetric and various chromatographic methods for quantitative determination of colchicine, each of them presenting a series of advantages and disadvantages. As an alternative, we proposed the use of a densitometric determination for colchicine allowing the determination of this alkaloid from pharmaceutical products, as well from seeds of meadow saffron. The total alkaloid extract was separated by Thin-Layer Chromatography using Silicagel 60F(254) layers and a mixture of chloroform:acetone:diethylamine (5:4:1) as mobile phase. The same conditions were used for the determination from pharmaceutical products. Densitometric measurements were carried out at the absorption maximum (350 nm) of colchicine, the determinations being made by reflectance and by fluorescence. The peaks were optimized regarding to their area and shape by varying four scanning parameters (slit width and height, number of measurements and scanning speed). We established the calibration plot using pure colchicine in the range 50-600 ng mL(-1). The proposed method could be widely used in the pharmaceutical industry for the quick and accurate quantitative determination of colchicine because it eliminates the interferences given by other bioactive or degradation compounds. The method was characterized by validation parameters (linearity, accuracy, fidelity, sensitivity) and it was established its performances in comparison with an HPLC method and an official quantitative determination from the Romanian Pharmacopoeia X edition respectively.

Essential oils analysis. II. Mass spectra identification of terpene and phenylpropane derivatives.

Mass spectra are widely used in order to identify the peaks resulting from a chromatographic separation. The most common approach to solve the problem for unknowns on whom very little other structural information is available is the use of a retrieval algorithm and a reference mass spectra database. The wide variety of mass spectra recorded with different instruments under various experimental conditions can lead to erroneous results. In order to improve the accuracy of the results, we proposed earlier an identification algorithm, which combines the information obtained from both GC and MS fingerprints. This paper presents a new algorithm based on the comparison of the unknown mass spectra with several libraries (including Wiley and NIST) by using reverse and direct search algorithms respectively. The results of the comparisons were quantified with respect to the match quality and the interference compounds. A global match index for the comparison using all the above information was computed and the results were presented as the match probability. This index expresses more accurately the matches between unknown and all the available libraries mass spectra. In order to verify our algorithm, we tried to identify the compounds separated by GC-MSD from different species of Acorus calamus L. (Araceae) essential oils. The probability of the matches increases compared with the quality of matches resulting from Wiley and NIST libraries.

The development of spectrophotometric and electroanalytical methods for ascorbic acid and acetaminophen and their applications in the analysis of effervescent dosage forms.

The electroanalytical study of ascorbic acid, acetaminophen and of several mixtures of these compounds in different ratios has been made by using a carbon paste electrode (CPE-graphite:solid paraffin 2:1) as working electrode and an Ag/AgCl reference electrode. The potential curves were recorded using different concentrations of ascorbic acid and acetaminophen by measuring samples between 10 and 50 microl. The oxidation reactions were studied in a potential range from -0.1 to +1.3 V with different sweep rates, at different current sensitivities, in stationary working conditions and stirring before each replicate. The oxidation of ascorbic acid occurs at +0.31 +/- 0.02 V and the oxidation of acetaminophen at +0.60 +/- 0.05 V; meanwhile, the current has a linear variation for the following concentration ranges: 10(-3)-10(-2) M for the ascorbic acid and 3 x 10(-6)-7.5 x 10(-3) M for acetaminophen (r2 = 0.999 for both ascorbic acid and acetaminophen). The mixtures of ascorbic acid and acetaminophen were made as follows: 1:1, 1:2, 1:3, 2:1, and 3:1. The studies revealed the alteration of the voltammograms processed according to the validation methodology. The best potential variation range for different current sensitivities, the influence of the sweep rate, of the solvent volume and of the pH were studied. The mutual interferences of the compounds in the mixtures and the electroactive compounds in the pharmaceutical dosage forms, especially effervescent ones, also made the object of the research. The same mixtures were studied using the direct spectrophotometric method that revealed a lot of spectral interferences. In order to solve this problem, an appropriate separation or an indirect spectrophotometric method (the apparent content curves method) were used. The spectrophotometric and voltammetric methods developed were used to determine ascorbic acid and acetaminophen in different dosage forms (vials, tablets, suppositories and effervescent dosage forms). The results were compared with those obtained by other techniques.

The voltammetric study of 2-mercapto-5-phenylammino-1,3,4-thiadiazole using carbon paste electrodes.

A rapid and accurate voltammetric method for the quantitative determination of 2-mercapto-5-phenylammino-1,3,4-thiadiazole (MPATD) with carbon paste electrodes (CPE) has been developed. The study was made by cyclic voltammetry between -0.4 and +0.6 V with 50 mV s(-1) sweep rate in aqueous solution. After successive oxidation/reduction cycles we found a total oxidation of MPATD at +0.45 V. As the compound is oxidated, the reduction current peak increases at +0.13 V, indicating an irreversible process. Following only the oxidation process in the -0.1 to +0.6 V range, we investigated the optimum scan rates at different current densities and pH values (realised with buffers, pH between 1.0 and 10.0) with CPE versus Ag/AgCl reference electrode using linear sweep voltammetry. We found a good linear relation between the current peak height and concentration in a 2.5 x 10(-9)-1.25 x 10(-7) mol ml(-1). This method allows the quantitative detection of the MPATD as it or from dosage forms and biological media.

The potentiometric and spectrophotometric determination of dissociation constants for same 2-mercapto-5-R-amino-1,3,4-thiadiazole derivatives.

In order to establish the dissociation constants of organic compounds, the spectrophotometric and potentiometric methods are the most precise and useful ones. Comparing the results, we used both methods for three derivatives of 2-mercapto-5-R-amino-1,3,4-thiadiazole. For the pKa determination by the spectrophotometric method we measured the ratio between the concentration of dissociated and undissociated forms. The ratio was calculated from spectral data. The potentiometric method for pKa consists of measuring the pH values within a potentiometric titration with 0.1 M NaOH. The results proved a very low acid character of the derivatives. The pKa values were influenced by the properties of the amino group substituents, and the results confirm the theoretical considerations. The study confirms the thion-thiolic tautometry of the 2-mercapto-5-R-amino-1,3,4-thiadiazole derivates and their property of being ligands for the coordination of the cations of some representative and transitional metals, with application in the preconcentration, in the detection and the quantitative determination of polluting and toxic cations in environmental analysis.

Comparison of GC-MS and TLC techniques for asarone isomers determination.

Two chromatographic methods (GC-MS and TLC) have been developed for separation and determination of alpha and beta asarone from essential oils and alcoholic extracts. The study has been performed on the Acorus calamus (I) and Asarum europaeum (II) essential oils of Romanian origin and the alcoholic extract of Acorus calcamus L (III) and it is a consequence of the International Boards exigency regarding the presence of beta asarone in food, beverages and pharmaceuticals. The isomers were determined using both internal and external standard methods. Both SIM and SCAN techniques were used and the results were compared regarding the chromatographic resolution and interference compounds. The method exhibits good repeatability and low detection limit but is expensive and time consuming. The two isomers concentrations are 5.2- 6.7 microg ml(-1) (I), 460-510 microg ml(-1) (II) and 2.7 5.7 microg ml (III) for alpha asarone and 91-98 microg ml(-1) (I), 24-29 microg ml(-1) (II) and 88 97 microg ml(-1) (III) for beta asarone. The TLC method was developed as an alternative for the GC method. The separation was performed on silica gel plates using toluene: ethyl acetate 8:2 as mobile phase. The evaluation of the chromatograms was made by densitometry using multiple wavelength. The sum of the two isomers are between 80-120 microg ml(-1) (I) and 127-145 microg ml(-1) (III) using spectrophotometric detection and between 73-93 microg ml(-1) (I) and 99-105 microg ml(-1) (III) using fluorimetric detection. The results of the two chromatographic methods were compared. Even the GC is more sensitive, mathematical computations for spots optimization and interference elimination could improves the TLC quality results.

Essential oils analysis. I. Evaluation of essential oils composition using both GC and MS fingerprints.

The chemical nature of essential oils makes them suitable for analysis using a gas chromatography-mass selective detector (GC-MSD). Mass spectra (MS) libraries can not be used as unique and absolute criteria for the identification of chromatogram peaks. The wide variety of MS of the libraries, recorded in different conditions, can lead us to erroneous results. In order to increase the reliability of the analytical results, we used as identity criteria, both GC fingerprints resulted from the relative retention indices (RRI) and the recorded MS of the separated compounds. The two criteria have been quantified by their correlation with the standards. A new parameter called global composition evaluation index (I(GCMS)), which resulted from a well-balanced average of the two criteria, has been defined. Because the comparison of the results of the MS with databases is more accurate than the RRI, we considered that the ratio of the two criteria must be at least GC:MS 1:2. A database containing RRI of about 600 components, widely found in essential oils composition and separated on HP-5 column, was created. Two macros based on the Microsoft Excel spreadsheet were also created. The program offers the best 20 matches of each compound with the combined MS and RRI library. The composition of Romanian Acorus calamus L. essential oil was established and the results were compared with those obtained by 'classical' methods.

TLC-UV densitometric and GC-MSD methods for simultaneous quantification of morphine and codeine in poppy capsules.

Thin-layer chromatographic (TLC)-UV densitometric and gas-chromatographic-mass spectrometric detection (GC-MSD) methods were developed for simultaneous quantification of morphine and codeine in poppy capsules (Papaver somniferum). Morphine and codeine were isolated by extraction with chloroform: isopropanol (3:1, v/v) at pH = 8.5 and by solid-phase extraction on Snap-Cap cartridges at pH = 8.5. The TLC-UV densitometric quantification was performed by external standard method on silica gel plates using ethyl acetate: toluene: methanol: ammonia (68:17:10:5, v/v) as developing solvent and UV detection at 275 nm. For the GC-MSD analysis, the drugs were derivatized with acetic anhydride: pyridine (1:1, v/v) and separated on a 30 m HP5 capillary column. The quantification was performed using nalorphine as internal standard.

Spectrophotometric determination of fluoride in dosage forms and dental preparations.

The method is based upon the reaction between fluoride ions and the coloured complex of Fe(III) with methyl salicylate to form the stable, colourless hexaflouride complex of iron. The conditions of the method (pH, time and combination ratio) were studied and a standard curve was obtained for 0.01-0.08 mg NaF ml-1, at 525 nm. A study was conducted on interference with complexing anions of Fe(III), cations that react with fluoride ions and with common ingredients of dosage forms and dental preparations. The method was validated and the results showed good precision (100.16 +/- = 2.33%) comparable with that of other analytical methods. Good results were obtained in the spectrophotometric determination of fluoride ions in a stomatological gel and in a toothpaste.

A modified McLafferty rearrangement in the electron impact mass spectra of dansylated amino-acid methyl esters.

Electron impact mass spectra of dansylated amino-acids and their methyl esters show a very time intense peak at m/z 171. A systematic study failed to show the genesis and origin of this ion. The present work is devoted to the electron impact mass spectrometric (EIMS) analysis of the appearance of this ion m/z 171 in the spectra of dansylated amino-acid methyl esters and its diagnostic importance in the analysis of dansyl derivatives. A structural model for this study is offered by a series of N-alkylated aromatic sulphonamides. The EIMS spectra of these compounds indicate that the classic fragmentation is accompanied by hydrogen migration from aliphatic radicals to the aromatic ring in a manner analogous with dansylated amino-acids. A modified McLafferty rearrangement mechanism is proposed for this EI reaction. The metastable transitions and the deuterium-labelled compounds confirm this mechanism and the origin of the itinerant hydrogen.