High-Precision Measurements of 44Ca/40Ca Using Multiple-Collector Inductively Coupled Plasma Mass Spectrometry without Collision-Cell Technology.

Herein, we present a new method for determining the Ca isotopic composition of geological samples. To eliminate matrix elements from Ca, a column chromatography method was developed using a N,N,N'N' tetraoctyl-1,5-diglycolamide (TODGA) resin. The Ca isotopic compositions were measured by a multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) without collision cell equipment, especially that direct measurement to 44Ca/40Ca can be achieved. To mitigate the interference from 40Ar during 40Ca measurement, the cold plasma technique was used to suppress the Ar+ generation, resulting in a background Ar+ intensity of <300 mV, in contrast to the conventional hot plasma conditions, which typically yield thousands of volts for Ar+ intensities. Given the potential for a concentration mismatch between the sample and bracketed standard solutions to cause an intensive shift in measured Ca isotopic compositions, a correction for the [Ca] match is needed. To avoid matrix effects arising from residue matrix elements, it is crucial to limit the concentrations below 1% of Ca for most matrix elements (including Al, Mg, K, Na, and Sr) and below 1‰ for Fe. Notably, the tolerance of residue Sr is effectively improved compared to measurements with CC-MC-ICP-MS and traditional Hot-plasma-SSB-MC-ICP-MS methods with the conventional hot plasma technique, thereby lowering the complexity of column chemistry. The measured δ44/40Ca, δ44/42Ca, and ε40Ca values for eight reference materials agree well with previously reported values within analytical uncertainties. This method demonstrates long-term precision is better than 0.10‰ (two standard deviations) for both δ values (i.e., δ44/40Ca and δ44/42Ca). We anticipate that the proposed method will benefit the growth of the Ca isotope data set and foster an increase in the application of Ca isotope in Earth science studies.

Combination of mathematics and label-free proteomics for discovering keratin-derived specific peptide biomarkers to distinguish animal horn-derived traditional Chinese medicines.

Saiga antelope horn and Rhinoceros horn have been used in traditional Chinese medicine for thousands of years. However, due to the protection of wildlife, the application of these rare animal horns has been restricted or prohibited. Therefore, water buffalo horn, goat horn, and yak horn have been applied as alternatives to Rhinoceros horn or Saiga antelope horn in a clinic. It is extremely difficult to distinguish normal animal horns in powdered or decocted form, especially identifying related species such as water buffalo horn, yak horn, and cattle horn. In this work, mathematics set and label-free proteomics analysis were combined for discovering keratin-derived specific peptide biomarkers. By using mathematics set analysis after nano liquid chromatography-tandem mass spectrometry-based proteomics, the selected species-specific peptides could be used to identify the authenticity of the Saiga antelope horn and goat horn. Furthermore, peptide biomarkers were selected to distinguish related species-derived horns, water buffalo horn, yak horn, and cattle horn. In total, eight peptide biomarkers were selected and applied for simultaneously distinguishing different horn samples. The present strategy provides a method for peptide biomarkers discovery and also has positive significance for ensuring the quality and efficacy of animal horn-derived traditional Chinese medicines and their products.

Application of a "Continuous-Acquisition-Method" to potassium isotope measurements by multi-collector inductively coupled plasma mass spectrometry.

RATIONALE: The very small mass difference between 41 K and 40 ArH+ makes the flat, hydride interference-free peak shoulders very narrow (0.002-0.003 m/z unit), bringing a number of analytical challenges when measuring K isotopic compositions by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). In traditional Sequence Run mode, the parameters are loaded every line of the sequence which can introduce tiny drifts of tune parameters and mass peaks. This may occasionally lead to the failure of K isotope measurements when mass drifts exceed 0.002 m/z unit. It is thus essential to keep the tune parameters, especially the magnet current, very stable to achieve high-precision K isotopic compositions. METHOD: We developed a "Continuous-Acquisition-Method" (CAM) MC-ICP-MS Run mode to improve the stability when determining K isotopes. Two sets of experiments were designed: (a) Stability test: measuring a single pure K solution (viz. NIST-999c) for ~3 h and comparing the stability of the two run modes; and (b) GSB-K test: measuring our inhouse pure K standard solution (GSB-K) in both run modes and comparing the accuracy and precision. RESULTS: The traditional Sequence Run mode only kept the MC-ICP-MS system stable for the first ~1.5 h during the ~3-h test, with an offset of the mass peaks of ~0.003 m/z unit. The CAM Run mode yielded higher stability during the whole test (~3 h), with a peak shift <0.0004 m/z unit. Measurement of the GSB-K standard solution in Sequence Run and CAM Run modes gives identical δ41 K values when the magnet was kept stable, with the CAM Run mode offering a better precision and keeping the instrument stable for longer time. CONCLUSIONS: The MC-ICP-MS CAM Run mode shows higher stability and better precision. It is, therefore, good for high-precision K isotope measurements.

[Effect of serum containing Xihuang pill on proliferation of human breast cancer cell line MDA-MB-435 and MCF-7 Cells].

To study the effect of serum containing Xihuang pill on the proliferation of human breast cancer cell lines MDA-MB-435 and MCF-7 and the gene and protein expressions of Bcl-2, Bax, TP53, in order to explore the effect and mechanism of Xihuang pill in resisting breast cancer. The serum of the rats was prepared by the method of MTT assay. The expressions of Bcl-2 and Bax were detected by RT-PCR. The serum levels of Bcl-2 and Bax and the mRNA expression of TP53 were detected by immunofluorescence. The rats with serum containing Xihuang pill could inhibit the proliferation of MDA-MB-435 cells and MCF-7 cells (P<0.05). The serum containing Xihuang pill increased TP53 and Bax in MDA-MB-435 cells (P<0.05), and the ratio of Bcl-2/Bax was decreased (P<0.05). Meanwhile, the serum containing Xihuang pill could up-regulate the mRNA expression of Bax in MCF-7 cells and decrease the expression of Bcl (P<0.05), but there was no significant difference between the expression of TP53mRNA and Bax protein expressions after the treatment of MCF-7 cells with Xihuang pill serum. Serum containing Xihuang pill can induce the apoptosis of human breast cancer cells, and the mechanism of estrogen receptor-negative breast cancer cell apoptosis may be induced by up-regulating the mRNA expression of TP53, which can induce the expression of Bax and promote the metastasis of Bax to mitochondria, and ultimately play the role of inducing apoptosis.