Low-pressure,microwave-induced plasma spectrometry method for the determination of subnanogram quantities of mercury: Application to mercury-carboxypeptidase analysis

A simple, sensitive, and rapid method for the determination of subnanogram quantities of mercury has been devised using a tantalum-filament vaporization system and low-pressure, microwave-induced emission spectrometry. This method is applied to the analysis of mercury-substituted carboxypeptidase with a sample volume of 5 μl and an analysis time of 3 min. The coefficient of variation for 2 × 10⁻¹⁰ g of mercury in mercury-carboxypeptidase is 6.0%, and the detection limit is 3 × 10⁻¹² g.     

Rapid metal speciation of cell culture media using reversed-phase separations and inductively coupled plasma optical emission spectrometry

Cell culture media metal content is critical in mammalian cell growth and monoclonal antibody productivity. The variability in metal concentrations has multiple sources of origin. As such, there is a need to analyze media before, during, and after production. Furthermore, it is not the simple presence of a given metal that can impact processes, but also their chemical form that is, speciation. To a first approximation, it is instructive to simply and quickly ascertain if the metals exist as inorganic (free metal) ions or are part of an organometallic complex (ligated). Here we present a simple workflow involving the capture of ligated metals on a fiber stationary phase with passage of the free ions to an inductively coupled plasma optical emission spectrometry for quantification; the captured species are subsequently eluted for quantification. This first level of speciation (free vs. ligated) can be informative towards sources of contaminant metal species and means to assess bioreactor processes.     

Fast atom bombardment mass spectrometry of estrogen glucuronides and sulfates

Fast atom bombardment (FAB) mass spectra of 13 intact, underivatized glucuronides and/or sulfate salts are reported. Spectra are characterized by abundant ions formed by attachment of a proton, [M+H]+, or of an alkali ion, [M+alkali]+, to the glucuronide or sulfate salt. Fragment ions were of low intensity. FAB spectra can be used to obtain the molecular weight of a sample, to assess its purity and to identify the nature of the alkali of the glucuronide or sulfate salt.     

Structure and antimicrobial activity of some new azopyrazolone chelates of Ni(II) and Cu(II) acetates, sulfates, and nitrates

Four coordinate Ni(II) and Cu(II) chelates formed by reaction of two azopyrazolone derivatives with metal sulfate, acetate, or nitrate are described. It is concluded that the ligands possess tautomeric equilibria and can coordinate to the metal ion as neutral or monobasic bidentates. The so-obtained complexes are characterized by elemental and thermal analyses, IR and electronic spectra, as well as conductivity measurements. A pseudo-tetrahedral polymeric structure is proposed for all the complexes in which the acetate, nitrate, or sulfate is attached to the metal ion in the bridging bidentate mode. It is observed that the chelates formed are more potent as antimicrobial agents than the free ligands.     

Multielement determination in small samples of human milk by inductively coupled plasma atomic emission spectrometry

Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used for routine analysis of small samples of human milk. The concentrations of calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), phosphorus (P), and zinc (Zn) were determined in 203 milk samples from postpartum women at different stages of lactation after stepwise digestion in HNO₃, HCIO₄, and H₂O₂ under heat. Validation of the procedure was achieved using certified reference material of bovine liver (NBS 1577) with mean recoveries of 103.5%. The concentrations of the above elements in milk matrix were comparable with previously reported values. The analytical results from breast milk will provide reference information for mineral studies of Brazilian mothers and breast-fed infants.     

Analysis of sulfates on low molecular weight heparin using mass spectrometry: structural characterization of enoxaparin

Introduction: Structural characterization of low molecular weight heparin (LMWH) is critical to meet biosimilarity standards. In this context, the review focuses on structural analysis of labile sulfates attached to the side-groups of LMWH using mass spectrometry. A comprehensive review of this topic will help readers to identify key strategies for tackling the problem related to sulfate loss. At the same time, various mass spectrometry techniques are presented to facilitate compositional analysis of LMWH, mainly enoxaparin.

Areas covered: This review summarizes findings on mass spectrometry application for LMWH, including modulation of sulfates, using enzymology and sample preparation approaches. Furthermore, popular open-source software packages for automated spectral data interpretation are also discussed. Successful use of LC/MS can decipher structural composition for LMWH and help evaluate their sameness or biosimilarity with the innovator molecule. Overall, the literature has been searched using PubMed by typing various search queries such as ‘enoxaparin’, ‘mass spectrometry’, ‘low molecular weight heparin’, ‘structural characterization’, etc.

Expert commentary: This section highlights clinically relevant areas that need improvement to achieve satisfactory commercialization of LMWHs. It also primarily emphasizes the advancements in instrumentation related to mass spectrometry, and discusses building automated software for data interpretation and analysis.     

Microwaves and the cell membrane. II. Temperature, plasma, and oxygen mediate microwave-induced membrane permeability in the erythrocyte

Microwaves (2450 MHz) are shown to increase 22Na permeability of rabbit erythrocytes for exposures only within the narrow temperature range of 17.7 to 19.5 degrees C (Tc) which coincides with a nonlinearity in the Arrhenius plot reflecting an apparent membrane phase transition. Significantly, this response is not observed for cholesterol-loaded erythrocyte membranes which exhibit a linear Arrhenius plot and no apparent phase transition at Tc. The permeability increase at Tc is a nonlinear function of absorbed power but is a linear function of the internal electric field strength of the sample and saturates at approximately 400 mW/g and 600 V/m, respectively. The permeability increase was found to be reversible and transient in that immediately following termination of exposure sodium influx is significantly reduced but returns to normal within 60 min. Extracellular factors exert a significant influence on the microwave effect. The presence of plasma markedly potentiates the increase in 22Na permeability at Tc. Oxygen also modulates the microwave effect with relative hypoxia (5 mm Hg) and hyperoxia (760 mm Hg) enhancing the permeability increase. In contrast, the presence of two antioxidants, ascorbic acid or mercaptoethanol, inhibits the effect. These findings raise important questions about the physical and chemical nature of microwave interactions with cell membranes and also shed light on earlier studies reporting either positive or negative effects on membrane permeability.     

Sterilization of bacteria, yeast, and bacterial endospores by atmospheric-pressure cold plasma using helium and oxygen

Atmospheric-pressure cold plasma (APCP) using helium/oxygen was developed and tested as a suitable sterilization method in a clinical environment. The sterilizing effect of this method is not due to UV light, which is known to be the major sterilization factor of APCP, but instead results from the action of reactive oxygen radicals. Escherichia coli, Staphylococcus aureus, and Saccharomyces cerevisiae deposited on a nitrocellulose filter membrane or Bacillus subtilis spores deposited on polypropylene plates were exposed to helium/oxygen plasma generated with AC input power at 10 kHz, 6 kV. After plasma treatment, nitrocellulose filter membranes were overlaid on fresh solid media and CFUs were counted after incubation overnight. D-values were 18 sec for E. coli, 19 sec for S. aureus, 1 min 55 sec for S. cerevisiae, and 14 min for B. subtilis spores. D-values of bacteria and yeast were dependent on the initial inoculation concentration, while the D-value of B. subtilis spores showed no correlation. When treated cells were observed with a scanning electron microscope, E. coli was more heavily damaged than S. aureus, S. cerevisiae exhibited peeling, and B. subtilis spores exhibited shrunken morphology. Results showed that APCP using helium/oxygen has many advantages as a sterilization method, especially in a clinical environment with conditions such as stable temperature, unlimited sample size, and no harmful gas production.     

Secondary structure of human plasma fibronectin: conformational change induced by calf alveolar heparan sulfates

The quantitative analysis of circular dichroic spectra of native human plasma fibronectin according to the method of Provencher and Gl?ckner [Provencher, S. W., & Gl?ckner, J. (1981) Biochemistry 20, 33-37] indicated the presence of beta-sheet (79%), beta-turn (21%), but no alpha-helix or random coil in the secondary structure. The calf alveolar heparan sulfates induced a change in the conformation of fibronectin: the magnitude of the change depended on the molecular properties of the particular heparan sulfate preparations.     

Candida mogii and Debaryomyces hansenii yeast development in the presence of metal chlorides

The yeasts Candida mogii 2 and Debaryomyces hansenii 8 isolated from salted fish spawn in the process of its storage were found to be capable of growth in 4 M KCl, 3 M MgCl2, 2.5 M NaCl, 1.5 BaCl2 and 1 M CaCl2. The activity of water (aw) in these solutions varied from 0.983 to 0.719; the maximum osmotic pressure was 380 atm. The cultures grew also in a 3 M sucrose solution, at low concentrations of osmotically active substances and without them. Therefore, they can be regarded as osmotolerant microorganisms. The osmotolerance of the cultures decreased with temperature of solutions. The absence of growth or weak growth in solutions of certain other chlorides should be attributed to toxicity of cations.     

Research on sensing characteristics of third-order runway series symmetric microring resonator based on hybrid plasma waveguide and metal insulator metal

In this paper, a high-sensitivity refractive index sensor based on a hybrid plasma waveguide and metal–insulator–metal waveguide combined third-order runway series mosaic microring resonator is proposed. In this structure, a GaAs waveguide ring surrounds a gold waveguide ring in the middle, and the innermost layer is a disk made of gold material. The outer groove waveguide is composed of GaAs-air-alloy, and the inner groove waveguide is made of the Gold-Air-Gold material disc. By filling different substances in the groove, the change of refractive index will affect the optical signal strength of the output spectrum. The finite element method simulates the transmission spectrum and electric field distribution of the sensor structure. The amplitude coupling coefficient and attenuation factor affecting the resonator's performance are analyzed, and the structural parameters of the slot waveguide are optimized. The numerical simulation results show that the sensor quality factor of this structure is 1.54 × 10⁴, the sensitivity is 1.2 × 10³ nm/RIU which is about 1.5 times higher than that of the Si ring with the same structure, the detection limit can reach 8.1892 × 10⁻⁷ RIU, and the free spectral range can reach 109 nm. Compared with the traditional microring structure, this microring has higher design freedom and free spectral range and is more suitable for producing biosensors with high sensitivity, low detection limit, and multi-parameter measurement.     

Composition of the major elements and trace elements of 10 methanogenic bacteria determined by inductively coupled plasma emission spectrometry

The elemental composition of 10 methanogenic species was determined by inductively coupled plasma emission spectrometry and by a C-H-N-analyzer. The 10 species were representative of all three orders of the methanogens and were cultivated under defined conditions. Special emphasis was given toMethanosarcina barkeri, represented by 5 strains and cultivated on various substrates. The following elements with the lowest and highest values in parentheses were determined: C (37–44%, w/w), H (5.5–6.5%), N (9.5–12,8%); Na (0.3–4.0%), K (0.13–5.0%), S (0.56–1.2%), P (0.5–2.8%), Ca (order I: 85–550 ppm; order II: 1000–4500 ppm), Mg (0.09–0.53%), Fe (0.07–0.28%), Ni (65–180 ppm), Co (10–120 ppm). Mo (10–70 ppm), Zn (50–630 ppm), Cu (<10–160 ppm), Mn (<5–25 ppm). The biggest variations were found with respect to N and K, which both seem to have important physiological functions. Although it is unknown whether zinc and copper are essential trace elements for methanogens, all investigated species contained remarkably high zinc contents, whereas copper seemed to be present only in some species.     

Simultaneous quantification of cholesterol sulfate,androgen sulfates,and progestagen sulfates in human serum by LC-MS/MS

Steroids are primarily present in human fluids in their sulfated forms. Profiling of these compounds is important from both diagnostic and physiological points of view. Here, we present a novel method for the quantification of 11 intact steroid sulfates in human serum by LC-MS/MS. The compounds analyzed in our method, some of which are quantified for the first time in blood, include cholesterol sulfate, pregnenolone sulfate, 17-hydroxy-pregnenolone sulfate, 16-α-hydroxy-dehydroepiandrosterone sulfate, dehydroepiandrosterone sulfate, androstenediol sulfate, androsterone sulfate, epiandrosterone sulfate, testosterone sulfate, epitestosterone sulfate, and dihydrotestosterone sulfate. The assay was conceived to quantify sulfated steroids in a broad range of concentrations, requiring only 300 μl of serum. The method has been validated and its performance was studied at three quality controls, selected for each compound according to its physiological concentration. The assay showed good linearity (R² > 0.99) and recovery for all the compounds, with limits of quantification ranging between 1 and 80 ng/ml. Averaged intra-day and between-day precisions (coefficient of variation) and accuracies (relative errors) were below 10%. The method has been successfully applied to study the sulfated steroidome in diseases such as steroid sulfatase deficiency, proving its diagnostic value. This is, to our best knowledge, the most comprehensive method available for the quantification of sulfated steroids in human blood.     

Arginase, nitrates, and nitrites in the blood plasma and erythrocytes in hypertension and after therapy with lisinopril and simvastatin

Arginase activity in erythrocytes is higher in patients with arterial hypertension and atherosclerosis as compared with healthy patients. Therapy with either lisinopril alone or in combination with simvastatin for 3–6 months causes a decrease in the arginase activity to the control level. Both the monotherapy and the combination therapy increased the concentrations of N₂⁻, N₃⁻, and total N₂⁻ + N₃⁻ in the plasma of hypertensive patients. The N₂⁻ + N₃⁻ concentration in erythrocytes decreases in hypertensive patients but is completely restored after therapy with lisinopril alone or in combination with simvastatin. Thus, lisinopril and lisinopril plus simvastatin display a pronounced and equal normalizing effect on arginase activity in human erythrocytes, which is elevated in hypertension, as well as on the endothelial nitric oxide synthase activity, which is decreased in hypertension.     

Bile acid sulfates. II. Formation, metabolism, and excretion of lithocholic acid sulfates in the rat

Sulfate esterification has been shown previously to be a prominent feature of lithocholate metabolism in man. These studies were undertaken to ascertain whether this metabolic pathway is also present in rats, and to investigate the physiological significance of bile acid sulfate formation. Lithocholic acid-24-(14)C was administered to bile fistula rats, and sulfated metabolites were identified in bile by chromatographic and appropriate degradative procedures. They constituted only a small fraction (2-9%) of the total metabolites but a more significant fraction (about 20%) of the secreted monohydroxy bile acids, most of the lithocholate having been hydroxylated by the rat liver. When sulfated glycolithocholate was administered orally, it was absorbed from the intestine without loss of the sulfate, presumably by active transport, and secreted intact into the bile. In comparison with non-sulfated lithocholate, an unusually large fraction (24%) of the sulfated bile acid was excreted in the urine, and fecal excretion took place more rapidly. Both the amino acid and sulfate moieties were extensively removed prior to excretion in the feces. Hydroxylation of bile acid sulfates or sulfation of polyhydroxylated bile acids did not occur to any great extent, if at all.     

Examination of metal mobilization from a gunshot by scanning acoustic microscopy,scanning electron microscopy,energy-dispersive X-ray spectroscopy,and inductively coupled plasma optical emission spectroscopy: a case report

Background

Projectile foreign bodies are known to cause chronic heavy metal toxicity due to the release of metal into the bloodstream. However, the local effect around the metallic object has not been investigated and the main goal of our study is to examine the influence of the object in close proximity of the object.

Case presentation

A 36-year-old Caucasian woman with one metallic pellet close to her sciatic nerve due to a previous shotgun injury at the gluteal area presented with a diagnosis of recurrent lumbar disk herniation at L4–5 level. A physical examination confirmed chronic neuropathy and she underwent a two-stage surgery. The surgery included removal of the foreign body, followed by discectomy and fusion at the involved level. During the removal of the metallic foreign body, a tissue sample around the pellet and another tissue sample from a remote area were obtained. The samples were analyzed by scanning acoustic microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Lead, chromium, copper, cadmium, iron, manganese, selenium, and zinc elements in tissue, blood, and serum specimens were detected by inductively coupled plasma optical emission spectroscopy.

Conclusions

An acoustic impedance map of the tissue closer to the metallic body showed higher values indicating further accumulation of elements. Energy-dispersive X-ray spectroscopy results confirmed scanning acoustic microscopy results by measuring a higher concentration of elements closer to the metallic body. Scanning electron microscopy images showed that original structure was not disturbed far away; however, deformation of the structure existed in the tissue closer to the foreign body. Element analysis showed that element levels within blood and serum were more or less within acceptable ranges; on the other hand, element levels within the tissues showed pronounced differences indicating primarily lead intoxication in the proximity of the metallic body. We can state that residues of metallic foreign bodies of gunshot injuries cause chronic metal infiltration to the surrounding tissue and induce significant damage to nearby neural elements; this is supported by the results of scanning acoustic microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and inductively coupled plasma optical emission spectroscopy.

     

Peak capacity of ion mobility mass spectrometry: separation of peptides in helium buffer gas

Advances in the field of proteomics depend upon the development of high-throughput separation methods. Ion mobility-mass spectrometry is a fast separation method (separations on the millisecond time-scale), which has potential for peptide complex mixture analysis. Possible disadvantages of this technique center around the lack of orthogonality between separation based on ion mobility and separation based on mass. In order to examine the utility of ion mobility-mass spectrometry, the peak capacity (phi) of the technique was estimated by subjecting a large dataset of peptides to linear regression analysis to determine an average trend for tryptic peptides. This trend-line, along with the deviation from a linear relationship observed for this dataset, was used to define the separation space for ion mobility-mass spectrometry. Using the maximum deviation found in the dataset (+/-11%) the peak capacity of ion mobility-mass spectrometry is approximately 2600 peptides. These results are discussed in light of other factors that may increase the peak capacity of ion mobility-mass spectrometry (i.e. multiple trends in the data resulting from multiple classes of compounds present in a sample) and current liquid chromatography approaches to complex peptide mixture analysis.     

Decomposition of biological macromolecules by plasma generated with helium and oxygen

In this study, we attempted to characterize the biomolecular effects of an atmospheric pressure cold plasma (APCP) system which utilizes helium/oxygen (He/O(2)). APCP using He/O(2) generates a low level of UV while generating reactive oxygen radicals which probably serve as the primary factor in sterilization; these reactive oxygen radicals have the advantage of being capable to access the interiors of the structures of microbial cells. The damaging effects of plasma exposure on polypeptides, DNA, and enzyme proteins in the cell were assessed using biochemical methods.