Chelating agents for human diseases related to aluminium overload

The aim of this review is to give a general view on the current status of the role of aluminium in human health and disease. The main aspects of aluminium metabolism in humans are covered, summarizing the state of knowledge on the absorption, distribution, retention and excretion of aluminium, giving particular emphasis to the main metabolic pathways of this metal ion in different organs. Then the pathological consequences of aluminium overload in man, its role in neurodegenerative diseases and the emerging implication of this metal ions in different pathologies are treated. Finally, the function of different chelators utilized in clinical practice in the therapy of aluminium depending diseases is discussed and the latest studies on aluminium chelators are presented. Some emphasis is given to the parallelism between iron and aluminium chelators, and in particular interesting correlations between structural parameters of these two trivalent metal ions are presented.     

Determination of pentane in human breath by gas chromatography

A new procedure, requiring expired sample volumes of approximately 2L, has been developed for the quantitative determination of n-pentane in human breath. The methodology capitalizes on the superior resolving power and separating efficiency of the open tubular capillary column and incorporates an effective prechromatographic cryofocusing technique. Molecular sieve is used to simultaneously remove moisture and carbon dioxide from breath samples which are “spiked” with an internal standard to optimize the validity of analysis. Reproducible data for both internal standard spiking (CV = 5.8%) and sample n-pentane level (CV = 3.2%) have been obtained, together with a mean recovery of 104%. Preliminary data show n-pentane levels in normal female subjects (n = 10) to range from 0.62 to 3.16 nmole/L (mean 1.76 nmole/L) and in males (n = 10) from 3.20 to 8.76 nmole/L (mean 5.66 nmole/L).     

Characterization of propofol in human breath of patients undergoing anesthesia

Ion mobility spectrometry coupled to a multi-capillary column (MCC/IMS) was used in anesthesia to detect signals related to Propofol in the breath directly. First time both positive and negative ions were investigated. It was found, that the detection limit in the negative mode is lower as in the positive one. Results of experiments with and without a bolus of Propofol were discussed with respect to kinetic models.     

Analysis of aldehydes in human exhaled breath condensates by in-tube SPME-HPLC

In this paper, polypyrrole/graphene (PPy/G) composite coating was prepared by a facile electrochemical polymerization strategy on the inner surface of a stainless steel (SS) tube. Based on the coating tube, a novel online in-tube solid-phase microextraction -high performance liquid chromatography (IT-SPME-HPLC) was developed and applied for the extraction of aldehydes in the human exhaled breath condensates (EBC). The hybrid PPy/G nanocomposite exhibits remarkable chemical and mechanical stability, high selectivity, and satisfactory extraction performance toward aldehyde compounds. Moreover, the proposed online IT-SPME-HPLC method possesses numerous superiorities, such as time and cost saving, process simplicity, high precision and sensitivity. Some parameters related to extraction efficiency were optimized systematically. Under the optimal conditions, the recoveries of the aldehyde compounds at three spiked concentration levels varied in the range of 85%–117%. Good linearity was obtained with excellent correlation coefficients (R²) being larger than 0.994. The relative standard deviations (n = 5) of the method ranged from 1.8% to 11.3% and the limits of detection were between 2.3 and 3.3 nmol L⁻¹. The successful application of the proposed method in human EBC indicated that it is a promising approach for the determination of trace aldehyde metabolites in complex EBC samples.     

Determination of iodine concentration in aqueous solutions by proton activation analysis: preliminary results for digested human thyroids

The aim of our studies is to check the possibilities of using proton activation analysis as a competitive method over other analytical techniques applied for iodine determination. It is well known that long-term irradiation of biological samples leads to their decomposition and formation of gaseous radiolysis products, which increase the pressure inside the sample container. In case of using proton beam another problem with liquid samples appears. It is the production of ⁷Be via spallation reactions ¹⁶O(p, spall)⁷Be. The Compton effect from ⁷Be γ-line increases the detection limits for isotopes with low-energy γ-lines. AIC-144 cyclotron at The Niewodniczański Institute of Nuclear Physics Polish Academy of Science can accelerate protons up to energy of 60 MeV which is sufficient for (p,5n) reaction needed to obtain ¹²³I (T _1/2 = 13.27 h, Eγ = 159 keV, I = 83%) from stable ¹²⁷I, thus the Compton effect from ⁷Be was the main factor perturbing the analysis. Separation and removal of ⁷Be is required to improve the detection limit. The paper presents a method and an example of its application to the determination of iodine concentration in digested fragments of human thyroids obtained during surgical treatment of patients with different types of thyroid tumor.     

Recent advances in breath analysis to track human health by new enrichment technologies

Detection of biomarkers in exhaled breath has been gaining increasing attention as a tool for diagnosis of specific diseases. However, rapid and accurate quantification of biomarkers associated with specific diseases requires the use of analytical methods capable of fast sampling and preconcentration from breath matrix. In this regard, solid phase microextraction and needle trap technology are becoming increasingly popular in the field of breath analysis due to the unique benefits imparted by such methods, such as the integration of sampling, extraction, and preconcentration in a single step. This review discusses recent advances in breath analysis using these sample preparation techniques, providing a summary of recent developments of analytical methods based on breath volatile organic compounds analysis, including the successful identification of various biomarkers related to human diseases.     

Direct measurement of ammonia in simulated human breath using an inkjet-printed polyaniline nanoparticle sensor

A sensor fabricated from the inkjet-printed deposition of polyaniline nanoparticles onto a screen-printed silver interdigitated electrode was developed for the detection of ammonia in simulated human breath samples. Impedance analysis showed that exposure to ammonia gas could be measured at 962 Hz at which changes in resistance dominate due to the deprotonation of the polymer film. Sensors required minimal calibration and demonstrated excellent intra-electrode baseline drift (≤1.67%). Gases typically present in breath did not interfere with the sensor. Temperature and humidity were shown to have characteristic impedimetric and temporal effects on the sensor that could be distinguished from the response to ammonia. While impedance responses to ammonia could be detected from a single simulated breath, quantification was improved after the cumulative measurement of multiple breaths. The measurement of ammonia after 16 simulated breaths was linear in the range of 40–2175 ppbv (27–1514 μg m⁻³) (r² = 0.9963) with a theoretical limit of detection of 6.2 ppbv (4.1 μg m⁻³) (SN⁻¹ = 3).     

Breath biosensing: using electrochemical enzymatic sensors for detection of biomarkers in human breath

Detection of biomarkers for disease by noninvasive methods is critical for the early diagnosis and screening of disease, enabling prompt treatment. Breath biosensors are a viable option as the exhaled breath contains several biomarkers linked to lung cancer, oxidative stress, diabetes, and other diseases. Breath analysis has been achieved by advanced analytical techniques such as gas chromatography and infrared spectroscopy. However, electrochemical enzymatic breath biosensors offer a cost-effective, sensitive platform for biomarker detection without complex analysis and interpretation by trained laboratory personnel. This review aims to summarize recent advances in the field of electrochemical enzymatic breath biosensors and offer future opportunities from other applications of nonelectrochemical enzymatic breath biosensors.     

Determination of fentanyl in human breath by solid-phase microextraction and gas chromatography–mass spectrometry

Fentanyl, a kind of intravenous narcotic analgesic, is widely used in clinical anesthesia. As a potential pollution, it was detected in both the air of the cardiothoracic operating room and patients' expiratory circuit. However, whether the fentanyl in patients' expiratory circuit is exhaled by patients is unknown. In this study, breath samples were taken from the expiratory circuits of anesthetic machine linked to the patients who received intravenous fentanyl, a solid-phase microextraction (SPME) coupled with gas chromatography–mass spectrometry (GC–MS) method was developed to detect and quantify fentanyl in breath samples. The parameters influencing adsorption (extraction time, temperature,) and desorption (desorption time) of the analyte on the fiber were investigated and validated for method development. The developed method was proved to be simple, easy, and inexpensive and offer high sensitivity and reproducibility. Linear range was obtained from 0.05 ng/mL to 0.8 ng/mL. The limit of detection was 0.01 ng/mL while an interday precision of less than 12.13% (n = 5) could be achieved. Six patients were involved in this study; results showed presence of fentanyl in the breath of patients who received intravenous fentanyl, and fentanyl concentrations in breath varied from 6.00 to 20.89 pg/mL. In conclusion, fentanyl can be exhaled by patients who received intravenous fentanyl.     

Molecular mechanisms of polypeptide aggregation in human diseases

Protein aggregation is implicated in a plethora of neurodegenerative diseases. The proteins found to aggregate in these diseases are unrelated in their native structures and amino acid sequences, but form similar insoluble fibrils with characteristic cross-beta sheet morphologies called amyloid in the aggregated state. While both the mechanism of aggregation and the structure of the aggregates are not fully understood at the molecular level, recent studies provide strong support for the idea that protein aggregation into highly stable, insoluble amyloid structures is a general property of the polypeptide chain. For proteins with a unique native state, it is known that aggregation occurs under conditions that promote native-state destabilization in vitro and in vivo. Taken together, the results of several important recent investigations suggest three broad molecular frameworks that may underlie the conversion of normally soluble peptides and proteins into insoluble amyloid fibrils: (1) edge-strand hydrogen bonding, (2) domain-swapping, and (3) self-association of amyloidogenic fragments. We argue that these underlying scenarios are not mutually exclusive and may be protein-dependent - i.e., a protein with a high content of hinge-regions may aggregate via a runaway domain-swap, whereas a protein with a high content of amyloidogenic fragments may aggregate primarily by the self-association of these fragments. These different scenarios provide frameworks to understand the molecular mechanism of polypeptide aggregation.     

Application of the photoionization detector for the determination of ethanol in aqueous solutions and human breath

A determination of ethanol is described, which is based on a purging system in conjunction with a photoionization detector. With that system a fast and reliable determination of ethanol in aqueous solutions is possible. The system has been used for the analysis of wine. The 3-detection limit has been 0.005% ethanol, the relative standard deviation 4.8 to 6.0% and the time constant of the entire analytical system 20 s. The photoionization detector has been also applied to the analysis of artificial and genuine human breath. A comparison with gas-chromatography and non-dispersive IR-detection has been proven the reliability of results.     

Application of the photoionization detector for the determination of ethanol in aqueous solutions and human breath

A determination of ethanol is described, which is based on a purging system in conjunction with a photoionization detector. With that system a fast and reliable determination of ethanol in aqueous solutions is possible. The system has been used for the analysis of wine. The 3delta-detection limit has been 0.005% ethanol, the relative standard deviation 4.8 to 6.0% and the time constant of the entire analytical system 20 s. The photoionization detector has been also applied to the analysis of artificial and genuine human breath. A comparison with gas-chromatography and non-dispersive IR-detection has been proven the reliability of results.     

Determination of volatile organic compounds in human breath for Helicobacter pylori detection by SPME-GC/MS

Helicobacter pylori living in the human stomach release volatile organic compounds (VOCs) that can be detected in expired air. The aim of the study was the application of breath analysis for bacteria detection. It was accomplished by determination of VOCs characteristic for patients with H. pylori and the analysis of gases released by bacteria in suspension. Solid-phase microextraction was applied as a selective technique for preconcentration and isolation of analytes. Gas chromatography coupled with mass spectrometry was used for the separation and identification of volatile analytes in breath samples and bacterial headspace. For data calculation and processing, discriminant and factor analyses were used. Endogenous substances such as isobutane, 2-butanone and ethyl acetate were detected in the breath of persons with H. pylori in the stomach and in the gaseous mixture released by the bacteria strain but they were not identified in the breath of healthy volunteers. The canonical analysis of discrimination functions showed a strong difference between the three examined groups. Knowledge of substances emitted by H. pylori with the application of an optimized breath analysis method might become a very useful tool for noninvasive detection of this bacterium.     

Alloy electrodes with high hydrogen overvoltage for analytical use in voltammetry. Some preliminary results

Liquid mercury and liquid diluted mercury amalgams have been the major electrode systems employed in voltammetry and related methods. This is mainly due to their high overvoltage to hydrogen, which enables the determination of heavy metals (zinc, nickel, cobalt, etc.) and other species with high negative half-wave potentials; the toxicity of mercury and liquid diluted mercury leads to ever increasing restrictions in their use. The use of such systems may even be forbidden in the future, at least in online systems for work in the field. Recent work, carried out in our laboratory, has demonstrated that a non-toxic solid dental amalgam may be used as the electrode material, conveniently replacing mercury. An extension of this work has shown that electrode materials comprising a metal or a compound with low hydrogen overvoltage change their hydrogen overvoltage properties substantially when contaminated with even small amounts of metals or compounds which show high hydrogen overvoltage. This extends greatly the range of potentially available electrode systems and thereby analytical possibilities of voltammetry. This new discovery also makes it possible to produce solid electrodes that have high overvoltage to hydrogen without any use of mercury.     

INAA results for metal traces in human whole blood

A special method of simultaneous serial INAA of about 18 elements in human whole blood samples has been developed. The frequency distribution of tracer contents in the blood of healthy people living in Georgia has been studied. The kinetic curves of age-dependent changes of various microelement contents in human blood over an interval from 15 to 110 years has been plotted.     

Reference materials for PAHs in foodstuffs: results of a preliminary intercomparison of methods in experienced laboratories

Summary A preliminary intercomparison of methods which can be applied to the determination of trace amounts of PAHs in coconut oil and green kale samples has been made under an interlaboratory cooperative analytical programme organised by the Community Bureau of Reference. The techniques which were utilised were glass-capillary gas chromatography with flame-ionisation or mass spectrometric detection, and high-performance liquid chromatography with fluorescence and/or ultra-violet detection. Analyses were made for five environmentally important PAHs and the results, the methods and some associated problems are discussed.

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Referenzmaterialien für PAKs in Lebensmitteln: Ergebnisse eines vorlÄufigen Ringversuchs erfahrener Laboratorien

     

Synthesis of iron oxide nanoparticles in a microfluidic device: preliminary results in a coaxial flow millichannel

A millimetric coaxial flow device operating under laminar flow has been designed to study the synthesis of iron oxide nanoparticles in a millichannel where the flow rate of the different reagents has been adjusted all over the experiments so that the magnetic and stable colloidal iron oxide particles with a size less than 7 nm have been prepared continuously.     

Gas chromatography — mass spectrometry in diagnosis of human metabolic diseases

Many human diseases result in characteristic changes in the biochemical composition of the cells and body fluids. Gas chromatography-mass spectrometry (GC-MS) and computer handling of the data are suitable for detecting such changes, e.g. the production of abnormal metabolites in a patient. The methods can be used to diagnose and study about 100 different metabolic disorders and have resulted in the discovery of 30 new inborn errors of metabolism.