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Results for “Spectrometry, X-Ray Emission”

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At least 19 recordsLinked to original sources
PubMed1979

Trace element determination in serum by proton-induced x-ray emission.

We report the use of proton-induced x-ray emission (PIXE) as an analytical method in clinical research. The experimental set-up and target preparation procedures are briefly discussed together with the methods of automatic data acquisition and analysis. Results from a clinical project involving rheumatoid patients receiving chrysotherapy are presented.

Arthritis, Rheumatoid↗
PubMed1977

Qualitative x-ray spectrometric study of E. histolytica trophozoite nuclei.

Qualitative X-ray energy spectroscopical analysis was performed in two strains of Entamoeba histolytica trophozoites: HK-9; NIH strain, and HM-2; IMSS strain, cultured in axenic and monoxenic conditions, respectively. The trophozoites were fixed in buffered-glutaraldehyde, embedded in Epon, thick sectioned )50-200 nm), and mounted on nickel grids. X-ray emissions were analyzed with an Ortec X-ray energy detector and multichannel and analyzer adapted to a transmission electron microscope. The study was concentrated on the refractive intranuclear bodies, characteristically numerous in axenically grown E. histolytica trophozoites. Nuclei of trophozoites with those intranuclear bodies contained phosphorus, calcium, and magnesium in greater amounts than nuclei not containing those structures. This was true for all axenically grown trophozoites and two monoxenically grown trophozoites which contained four intranuclear bodies. It is concluded that the composition of the refractive intranuclear bodies in E. histolytica trophozites does not appear to change with the culture conditions or with the composition of the culture media.

Calcium↗
PubMed2026

Assessing Metal Ion Assignment Accuracy in Protein Data Bank Models via Elemental Spectroscopy.

Accurate representation of metal ions in macromolecular structures is critical for chemical interpretation, computational modeling, and machine-learning methods that rely on Protein Data Bank (PDB) entries. However, the elemental identity of metals modeled in crystallographic structures is often inferred indirectly and rarely validated experimentally. Here, we combine Particle Induced X-ray Emission (PIXE) and X-ray Fluorescence Spectroscopy (XRFS) to determine the elemental composition of protein samples used to generate 70 deposited metalloprotein crystal structures. By analyzing the original protein material employed for crystallization, but before the addition of crystallization buffer solutions, we assess whether the modeled metal ions in deposited structures are consistent with experimentally detectable elemental content. We find that in a majority of cases, the metals modeled in the corresponding PDB entries are inconsistent with the metals present in the protein samples before crystallization, or that additional metals are present but not represented in the structural models. Spectroscopic results were integrated with automated crystallographic validation metrics, including real-space Z-difference (RSZD) analysis and systematic rerefinement, to evaluate atomic-number mismatch at metal sites. PIXE and XRFS show strong agreement for dominant elemental signals and provide complementary, scalable approaches for identifying suspect metal assignments. This work does not address physiological or functional metalation but instead highlights a widespread data integrity issue in deposited macromolecular structures, PDB-wide. These results establish an experimentally corroborated link between elemental identity and crystallographic validation metrics, enabling the large-scale detection of chemically inconsistent annotations in structural databases used for computational modeling and machine learning.

Databases, Protein↗
PubMed1978

Serum copper and zinc measurement in patients with osteogenic sarcoma.

Serum copper level (SCL), serum zinc level (SZL), and SCL/SZL ratio were measured in 18 patients with biopsy-proven osteogenic sarcoma. Measurements were made on sequentially collected serum samples beginning prior to the institution of therapy and continuing periodically until documented relapse. All patients were treated by curative resection and adjuvant therapy consisting of high dose methotrexate (with leucovorin rescue) with or without BCG immunotherapy. The SCL, SZI, and SCL/SZL determinations were made using proton-induced x-ray fluorescence spectrometry. SCL was significantly elevated (p less than .0001) in the 18 patients with primary untreated osteogenic sarcoma )173 +/- 30 microgram/dl) compared with a sex and age-matched normal group (115 +/- 16 microgram/dl). A significantly different SZL was not found, however, so that an elevated SCL/SZL ratio in the osteogenic sarcoma patients was primarily due to the altered SCL. SCL and SCL/SZL did not change significantly following curative surgery or become more abnormal in those patients who developed recurrent disease. The SCL and SCL/SZL were noted to be markedly elevated in those patients receiving BCG therapy, raising concern regarding the specificity of these tests as markers of tumor activity. SCL, SZL, and SCL/SZL did not appear useful as markers of tumor activity in patients with osteogenic sarcoma.

Adolescent↗
PubMed1978

A microprobe analysis of Gomori-positive glial cells in the rat arcuate nucleus.

Astrocytes and microglial cells in the arcuate nucleus of the rat hypothalamus contain lipofuscin-like granules which react with chrome alum gallocyanin and exhibit endogenous peroxidase activity. These granules were assessed with energy dispersive X-ray microanalysis and compared to neuronal dense bodies and glial cytoplasm. The granules are distinguished by a consistent content of sulphur and a frequent presence of calcium. The localization of other elements such as iron, copper, potassium and chlorine is impaired by methodical difficulties. The sulphur content as well as the endogenous peroxidase activity is interpreted as indicating a special variant of lipofuscin. The presence of calcium is discussed with respect to recent concepts of glia as a regulator of the ionic environment of the CNS.

Animals↗
PubMed1978

Changes in elemental composition of human chromosomes during a G-banding (ASG) and a C-banding (BSG) procedure.

Human chromosomes fixed in methanol-acetic acid have been examined by X-ray microanalysis, before, during and after a G-banding and a C-banding procedure. Phosphorus (representing mainly DNA), sulphur and calcium are the most prominent elements in untreated chromosomes. In the G-banding procedure, the calcium is lost during 2 x SSC treatment. In the C-banding procedure, calcium is lost in the preliminary HCl treatment. During the following barium hydroxide treatment a large amount of barium becomes attached to the chromosomes, but is lost again during the subsequent 2 x SSC treatment. In both banding techniques Giemsa staining produces large peaks for sulphur (thiazine dyes) and bromine (eosin), showing that both types of dyes are involved in the staining. Reduction in the phosphorus peak during these procedures may be partly due to extraction of DNA and other chromosomal components, but could also be due to absorption of phosphorus X-rays by heavy elements (barium and bromine).

Chromosomes, Human↗
PubMed1978

X-ray fluorescence analysis of lead in teeth of urban children in situ: correlation between the tooth lead level and the concentration of blood lead and free erythroporphyrins.

The tooth lead level of 30 lead-exposed children was measured in situ using an X-ray fluorescence technique. The tooth lead concentration divided by the child's age correlated with the free erythroporphyrin (FEP) (r = 0.51) and the blood lead levels (r = 0.31). The mean tooth lead concentrations of 10 Class IV children (FEP greater than or equal to 190 micrograms/100 ml; blood lead 30-80 micrograms/ml) was 14.5 +/- 5.5 ppm/year. Reexamination of the histories of children who had been classified as Class II or III, but who had tooth lead concentrations within 1 SD of the Class IV level, indicated that many of these children could also be considered to be Class IV children. When the x-ray fluorescence technique was used to screen an urban population of 300 children, the tooth lead values indicated that 72% of the children had been exposed to low levels of environmental lead. Six percent of the children were found to have tooth lead concentrations in excess of 9 ppm/year and within 1 SD of the mean value exhibited by Class IV children. These children were considered to have a high body lead burden. The percentage of children having an elevated tooth lead level is similar to the number previously reported using exfoliated deciduous teeth.

Child↗
PubMed1978

Reactivity of antiinflammatory and superoxide dismutase active Cu(II)-salicylates.

The activity of chelated Cu(II) with four different aspirin-like drugs in various superoxide dismutase assays was examined. Prior to these studies the oxidation state of the involved copper was measured by x-ray photoelectron spectrometry and was found to be +II throughout. All copper complexes were able to suppress the xanthine-xanthine oxidase mediated reduction of both cytochrome c and nitroblue tetrazolium as well as the formazan formation by KO2 in a specific manner. The hydroxylation of benzo-[alpha]-pyrene as well as the demethylation of 7-ethoxycoumarin using induced hepatic rat microsomes could be successfully inhibited by the employed Cu(II) chelates. Cu(II)-acetylsalicylate was the most active copper complex. Our findings support the proposal that Cu(II) chelates are the active forms of aspirin-like antiinflammatory agents.

Animals↗
PubMed1978

Dental x-ray spectrometry with an Si(Li) semiconductor.

Spectra from a dental x-ray apparatus with varying tube potentials and various added filters were measured with the use of an Si(Li) semiconductor. The mean energies of the spectra were calculated to estimate radiation qualities under various conditions. A phantom lip made of Arcylite was used to compare the attenuated quantities of radiation incident on the lip, according to the radiation quality, resulting from various tube potentials and added filtration.

Elementary Particles↗
PubMed2026

Elemental composition, structure and amount of contact between Xanthoria parietina symbionts.

As prominent examples for symbiotic interactions, the major part of lichens is built up by two different organisms, a photosynthetically active alga (photobiont) and a heterotrophic fungus (mycobiont). Given the hydrophobic coating of lichen symbionts in the lichen thallus by hydrophobins, the area of direct cell cell contact is of prime importance for the transfer of nutrients and signalling compounds between the symbionts. Genomic analyses reported cell wall remodelling during symbiont interaction. However, no detailed investigation of lichen symbiont interaction zone is available so far. Using Energy-dispersive X-ray spectroscopy (EDS), we show that elemental composition of both symbiont cell walls differs when in contact to the symbiont as opposed to those cell wall areas without contact. Both, nitrogen and sulfur content of cell walls, differ significantly in areas of symbiont cell contacts as compared to non-contact zones. NanoCT imaging revealed that about one fourth of the photosymbiont cell wall is in contact to mycobiont hyphae, and fungal cells have a significantly increased volume if in contact to photobiont cells. We provide a sub µm 3D model of the lichen Xanthoria parietina using nanoCT imaging to foster understanding of the symbiont interaction zone.

Symbiosis↗
PubMed1977

Polymeric cryoprotectants in the preservation of biological ultrastructure. II. Physiological effects.

A study has been made of the physiological effects of three non-penetrating polymeric cryoprotective agents on sixteen different plant and animal cells and tissues. The cryoprotectants, when used at concentrations at which they are effective in preventing ice-crystal formation, generally have a lower toxicity to cells and tissue than similar concentrations of glycerol. The relatively low toxicity of these substances suggests that they would be more suitable as cryoprotectants for morphological and analytical studies than the commonly used low molecular weight compounds.

Cell Survival↗
PubMed1977

Adherence controlling elements in ceramic-metal systems. I. Precious alloys.

Elemental analysis of two precious alloyceramic systems revealed the accumulation of Sn atoms within the interaction zone of couples subjected to a range of metal oxidation time; and varying total firing times. The source of Sn atoms which accumulated within the interaction zone was the opaque porcelain layer which contained an initially higher Sn concentration than the alloy. It is hypothesized that SnO2 provides continuity of electronic structure between alloy and ceramic structures and is a primary factor in controlling ceramic-metal adherence.

Chemical Phenomena↗
PubMed1978

Fluorine and tin uptake by enamel studied by x-ray photoelectron spectroscopy (ESCA).

ESCA has been combined with argon-ion etching to obtain depth profiles for SnF2-treated enamel. Three zones of products from the topical treatment are detected: a layer of tin oxide on the surface; fluoroapatite + hydroxyapatite at depths below about 0.2 micron; an intermediate layer CaF2, Sn(OH)2, Sn2PO4OH, and fluoroapatite between the two. Sn3F3PO4 was not detected.

Argon↗