Direct sub-atmospheric pressure ionization mass spectrometry: Evaporation/sublimation-driven ionization is amazing, fundamentally, and practically.

This paper covers direct sub-atmospheric pressure ionization mass spectrometry (MS). The discovery, applications, and mechanistic aspects of novel ionization processes for use in MS that are not based on the high-energy input from voltage, laser, and/or high temperature but on sublimation/evaporation within a region linking a higher to lower pressure and modulated by heat and collisions, are discussed, including how this new reality has guided a series of discoveries, instrument developments, and commercialization. A research focus, inter alia, is on how best to understand, improve, and use these novel ionization processes, which convert volatile and nonvolatile compounds from solids (sublimation) or liquids (evaporation) into gas-phase ions for analysis by MS providing reproducible, accurate, sensitive, and prompt results. Our perception on how these unprecedented versus traditional ionization processes/methods relate to each other, how they can be made to coexist on the same mass spectrometer, and an outlook on new and expanded applications (e.g., clinical, portable, fast, safe, and autonomous) is presented, and is based on ST's Opening lecture presentation at the Nordic Mass spectrometry Conference, Geilo, Norway, January 2023. Focus will be on matrix-assisted ionization (MAI) and solvent-assisted ionization (SAI) MS covering the period from 2010 to 2023; a potential paradigm shift in the making.

More inclusive or selective ionization for mass spectrometry using obstructive sonic spray ionization and voltage polarity switching.

RATIONALE: A new variation of sonicspray ionization (SSI) significantly enhances its sensitivity with an advantage of producing selective or more inclusive ionization by changing the polarity of the potential applied to an obstruction in the path of the SSI spray. This technique also provides high sensitivity with water solutions, which is difficult for electrospray ionization (ESI) without added organic solvent. METHODS: An Orbitrap Exactive mass spectrometer with an IonMax source heated electrospray ionization (ESI) probe operating at its maximum sheath gas setting was used for SSI. Both positive and negative polarities varying from 0.1 to 4 kV were applied to a metal obstruction positioned in the path of the spray using an atmospheric solid analysis probe. All mass spectra for this study were acquired in the positive ion mode. RESULTS: SSI using a variety of obstructions improved the observed analyte ion abundance of small molecules, peptides, and proteins by approximately two orders of magnitude. The addition of a DC or AC voltage to a metal obstruction further enhanced the abundance of analyte ions by an additional two orders of magnitude. The relative abundances of the detected positive ions were considerably altered by switching the voltage polarity on the obstruction. CONCLUSIONS: SSI with an obstruction improves the sensitivity of various samples compared with SSI. An applied voltage onto the obstruction further enhances the analyte ion abundances to approximately equal that of ESI but has the added advantage that switching the voltage polarity from positive to negative on the obstruction emphasizes different compounds present in the sample.

Automatic Detoxification Medicine Delivery by Thermo-Sensitive Poly(ethylene glycol)-Based Nanogels.

During the medication-assisted treatment of drug abuse, side effects and addiction liabilities are commonly observed. Thus, control of the medication dose is very important. According to body temperature abnormalities in drug abusers, a thermo-sensitive nanogel was synthesized as a drug carrier to automatically deliver detoxification medicines. This nanogel was prepared through the synthesis of polystyrene (PS) core microspheres, followed by coverage with a nonlinear poly(ethylene glycol)-based copolymer shell. The PS core microspheres were found to be an ideal hydrophobic core for loading the detoxification medicines effectively. The nonlinear poly(ethylene glycol)-based copolymer shell layer consisted of 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and oligo(ethylene glycol) methyl ether methacrylates (Mn = 300 g mol-1, MEO5MA). The monomer feeding molar ratio n(MEO2MA)/n(MEO5MA) of 1:3 enabled PS@P(MEO2MA-co-MEO5MA) nanogels to exhibit a distinguished colloidal stability and an adjustable volume phase transition temperature which is within the drug addicts' abnormally fluctuating temperature range. Importantly, it was found that the obtained PS@P(MEO2MA-co-MEO5MA) nanogels displayed good biocompatibility with rat aortic endothelial cells in the given concentration range. The nanogels also exhibited a satisfactory loading efficiency and thermo-sensitive/sustained release characteristics for three detoxification medicines: sinomenine, diltiazem and chlorpromazine.

Research on the Vitality Evaluation of Parks and Squares in Medium-Sized Chinese Cities from the Perspective of Urban Functional Areas.

Medium-sized cities are increasingly committed to the planning and construction of urban public spaces to meet people's demand for high-quality urban life. Parks and squares are important parts of urban public spaces, and their vitality represents the quality of public spaces to a certain extent and reflects the happiness index of urban residents. At present, the functional areas and transportation networks of medium-sized cities are still developing. Due to the influence of urban construction, the planning of parks and squares in medium-sized cities has not yet caught up to that in larger cities. This study analyzed a medium-sized city, Jiaozuo, as an example, with the help of point of interest (POI) data, OpenStreetMap road network density data and WorldPop population data. The vitality of parks and squares in different functional spaces in the main urban area in Jiaozuo was quantitatively evaluated in terms of the four following aspects: urban space functional area characteristics, travel vitality index of urban residents, park and square attractiveness and the regional service levels of parks and squares. The effects of functional mixing, traffic network density, population density and spatial distribution on the vitality of parks and squares in medium-sized cities were also studied. The results showed that (1) the functional mixing in the main urban area in Jiaozuo was characterized by a spatial distribution of high in the center and low in the surrounding areas, with the highest functional mixing in the central part of the Jiefang District; (2) the travel dynamics of urban residents were characterized by a clear development of concentric circles radiating in a circular pattern; (3) the levels of service in parks and squares were particularly high in Jiefang District, with a spatial distribution of Jiefang District > Shanyang District > Macun District > Zhongzhan District; (4) under the condition that the service levels of each district were the same, the vitality values of the existing parks and squares in each district were compared and, from high to low, were Jiefang District (1.0-3.5), Shanyang District (0.2-2.0), Macun District (0-1.4) and Zhongzhan District (0-1.2). Functional mixing, road networks and population density had significant impacts on the vitality of parks and squares. Based on our study on the division of urban functional areas, we expanded the study to include urban microspaces. By evaluating the vitality of existing parks and squares and analyzing the influencing factors of spatial vitality, we found that it would be helpful to adopt targeted strategies to improve spatial vitality. Considering the spatial layouts of parks and squares, planning and constructing high-vitality parks and squares would be conducive to the future development of medium-sized cities. The existence of high-vitality spaces could also help to realize the sustainable development of cities.

Multifunctional amphiphilic ionic liquid pathway to create water-based magnetic fluids and magnetically-driven mesoporous silica.

Amphiphilic ionic liquids, 1-alkyl-3-methylimidazolium chloride (C n mimCl with n = 10, 12, 14, 16) were firstly used as modifiers to construct a self-assembly bilayer on the surface of iron oxide nanoparticles for generation of highly stable, water-based magnetic fluids. Subsequently, a magnet-driven mesoporous silica was synthesized by in situ self-assembly in the bilayer C n mimCl-stabilized magnetic fluid using the C16mimCl as template and tetraethylorthosilicate (TEOS) as silicon source via a hydrothermal synthesis and following calcination procedure. A systematic study was carried out addressing the influence of the alkyl chain length of C n mimCl in the primary and secondary layers on the stability of magnetic fluids. The characterization of TEM, XRD, VSM, electrophoresis experiments, TGA and DTA showed that stable water-based magnetic fluids can be synthesized based on the assembly of the well-defined bilayer-C n mimCl structure with long-chain C16mimCl as secondary layer on the magnetite (Fe3O4) nanoparticles. The results of small and wide-angle XRD, TEM, VSM, and N2 absorption experiments indicated that the nano-scale magnetic Fe3O4 particles were inlayed into hexagonal p6mm mesoporous silica (MCM-41 type) framework. Importantly, it was found that the obtained Fe3O4/MCM-41 was an appropriate adsorbent for the adsorption of rhodamine B and methylene blue from their aqueous solution. In addition, the adsorbent could be separated and reclaimed fleetly from the solution under external magnetic field.

Long chain ionic liquid-assisted synthesis of PS/Pd beads and hierarchical porous Pd-SiO2.

Long-chain ionic liquid, 1-hexadecyl-3-methylimidazolium chloride (C16mimCl), was firstly used as a linking agent to construct polystyrene (PS)/C16mimCl/palladium (Pd) beads. Subsequently, the PS/C16mimCl/Pd beads were used as a macroporous templating agent and C16mimCl was used as a mesoporous templating agent to prepare Pd-loaded hierarchical porous silica. A systematic study was carried out addressing the influence of the amount of C16mimCl and the mass ratios of m(Pd)/m(PS) on the PS/C16mimCl/Pd beads and the Pd-loaded hierarchical porous structures. The samples were characterized by electrophoresis experiments, SEM, TEM, small-angle XRD, and N2 adsorption-desorption experiments. It was found that the coverage of citrate-coated Pd nanoparticles (Pd NPs) onto the PS beads can be simply tailored by changing the amount of C16mimCl and the mass ratios of m(Pd)/m(PS). The resultant Pd-loaded hierarchical porous silica possessed a 3D ordered macroporous skeleton with a specific surface area of up to 967 m2 g-1, ordered mesoporous silica walls (SBA-3 type) and well-dispersed Pd NPs anchored on the inner walls of the spherical macroporous hollow. Importantly, the obtained Pd-loaded hierarchical porous silica exhibited an enhanced catalytic activity for the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2.

Compositional monosaccharide analysis of transgenic corn glycoproteins by HPLC with fluorescence detection and LC-MS with sonic spray ionization.

Transgenic corn offers an attractive, cost-effective means for the large-scale production of engineered glycoproteins suitable for pharmaceutical purposes. A glycoprotein expressed in transgenic corn theoretically should not contain glycans because glycosylation sites have been genetically altered. A sensitive and reliable analytical method is developed to investigate this particular protein for the presence of glycans by monitoring the monosaccharide composition. Identification and quantitation of low-level monosaccharides in the glycoprotein hydrolyzate are accomplished by derivatization prior to high-performance liquid chromatography (HPLC)-fluorescence and liquid chromatography (LC)-sonic spray ionization (SSI)-mass spectrometry (MS) analyses. LC-SSI-MS is used to confirm the results from HPLC-fluorescence analysis and to positively identify the compositional monosaccharides. Glucosamine, glucose, mannose, arabinose, xylose, and sialic acid are found in the transgenic corn derived glycoprotein at less than one moiety per protein, which indicates heterogeneity of the particular glycoprotein. In addition to the compositional analysis of low-level monosaccharides in glycoprotein by HPLC-fluorescence, the utility of SSI for the LC-MS analysis of derivatized monosaccharides is demonstrated in this paper.

Direct interaction between Smad3, APC10, CDH1 and HEF1 in proteasomal degradation of HEF1.

BACKGROUND: The Transforming Growth Factor-beta (TGF-beta) regulates myriad cellular events by signaling through members of the Smad family signal transducers. As a key signal transducer of TGF-beta, Smad3 exhibits the property of receptor-activated transcriptional modulator and also the novel ability of regulating the proteasomal degradation of two Smad3 interacting proteins, SnoN and HEF1. It has been shown that Smad3 recruits two types of Ub E3 ligases, Smurf2 and the Anaphase Promoting Complex (APC), to mediate SnoN ubiquitination, thereby enhancing SnoN degradation. The molecular mechanisms underlying Smad3-regulated HEF1 degradation are not well understood. Furthermore, it is not clear how Smad3 recruits the APC complex. RESULTS: We detected physical interaction between Smad3 and an APC component APC10, as well as the interaction between HEF1 and CDH1, which is the substrate-interacting component within APC. Detailed domain mapping studies revealed distinct subdomains within the MH2 domain of Smad3 for binding to APC10 and HEF1 and suggests the formation of a complex of these four proteins (Smad3, HEF1, APC10 and CDH1). In addition, the protein levels of HEF1 are subjected to the regulation of overexpressed APC10 and CDH1. CONCLUSIONS: Our data suggests that Smad3 may recruit the APC complex via a direct interaction with the APC subunit APC10 to regulate the ubiquitination and degradation of its interactor HEF1, which is recognized as an ubiquitination substrate by the CDH1 subunit of the APC complex.

A novel link between the proteasome pathway and the signal transduction pathway of the bone morphogenetic proteins (BMPs).

BACKGROUND: The intracellular signaling events of the bone morphogenetic proteins (BMPs) involve the R-Smad family members Smad1, Smad5, Smad8 and the Co-Smad, Smad4. Smads are currently considered to be DNA-binding transcriptional modulators and shown to recruit the master transcriptional co-activator CBP/p300 for transcriptional activation. SNIP1 is a recently discovered novel repressor of CBP/p300. Currently, the detailed molecular mechanisms that allow R-Smads and Co-Smad to co-operatively modulate transcription events are not fully understood. RESULTS: Here we report a novel physical and functional link between Smad1 and the 26S proteasome that contributes to Smad1- and Smad4-mediated transcriptional regulation. Smad1 forms a complex with a proteasome beta subunit HsN3 and the ornithine decarboxylase antizyme (Az). The interaction is enhanced upon BMP type I receptor activation and occur prior to the incorporation of HsN3 into the mature 20S proteasome. Furthermore, BMPs trigger the translocation of Smad1, HsN3 and Az into the nucleus, where the novel CBP/p300 repressor protein SNIP1 is further recruited to Smad1/HsN3/Az complex and degraded in a Smad1-, Smad4- and Az-dependent fashion. The degradation of the CBP/p300 repressor SNIP1 is likely an essential step for Smad1-, Smad4-mediated transcriptional activation, since increased SNIP1 expression inhibits BMP-induced gene responses. CONCLUSIONS: Our studies thus add two additional important functional partners of Smad1 into the signaling web of BMPs and also suggest a novel mechanism for Smad1 and Smad4 to co-modulate transcription via regulating proteasomal degradation of CBP/p300 repressor SNIP1.

The 26S proteasome system in the signaling pathways of TGF-beta superfamily.

Recent studies of the Smad family proteins, which are the key signal transducers of the TGF-beta family ligands, have revealed the ability of Smads to interact with various components of the 26S proteasome system. Such interactions are now known to contribute to the regulation of Smad protein levels before and after Smad activation. Most importantly, such interactions are also shown to be an integral part of the signaling functions of Smads. Through a physical interaction with different ubiquitin E3 ligases (HECT family, SCF and APC complex), the TGF-beta/activin responsive Smad3 exhibits the novel ability to regulate the ubiquitination of several key regulators, such as the oncoprotein SnoN and the multi-domain docking protein HEF1. The proteasomal degradation of these two proteins links TGF-beta signaling to multiple signaling pathways involving SnoN and HEF1. Through the interaction with proteasome beta subunit HsN3 and the substrate marker protein ornithine decarboxylase antizyme (AZ), the BMP responsive Smad1 regulates the proteasomal targeting events that contribute to the degradation of Smad1 and its interacting proteins, one of which is SNIP1, a repressor of the transcriptional co-activator CBP/p300. Thus, the novel physical link between Smads and components in the 26S proteasome system allow the intracellular events triggered by the TGF-beta family ligands to connect with those induced by many other extracellular regulators, thereby forming an extremely complex signaling network to regulate a wide range of biological activities.

The immunophilin FKBP12: a molecular guardian of the TGF-beta family type I receptors.

FKBP12 as an immunophilin that binds to two well-known immunosuppressive macrolides, FK506 and rapamycin, has attracted immense attention and its role in mediating the immunosuppressive functions of these macrolides has been extensively studied. Since FKBP12 is a well-conserved protein among many species and is also highly expressed in almost all cells, it must play important roles in cellular function in the absence of macrolides. In one such a role, FKBP12 interacts with and regulates the functional state of the ryanodine Ca2+ channel receptor by altering protein conformation and coordinating multi-protein complex formation. This review summarizes another physiological role of FKBP12 as an interactor and a regulator of the type I serine/threonine kinase receptors of TGF-beta superfamily. Current data, derived from detailed biochemical studies as well as from functional studies in various systems, suggest that FKBP12 functions as a "guardian" for the type I receptors to prevent them from leaky signaling under sub-optimal ligand concentrations, thereby providing a molecular "gradient reader" for TGF-beta family morphogens. This aspect of FKBP12 function may be critical for cellular responsiveness to morphogenetic gradients of the TGF-beta family members during early development, serving to assure the translation of different ligand concentrations into different signaling readouts.

Comprehensive screening study of pesticide degradation via oxidation and hydrolysis.

This comprehensive study focused on the reactivity of a set of 62 pesticides via oxidization by free chlorine, monochloramine, chlorine dioxide, hydrogen peroxide, ozone, and permanganate; photodegradation with UV(254); and hydrolysis at pH 2, 7, and 12. Samples were analyzed using direct injection liquid chromatography-mass spectrometry detection or gas chromatography-electron capture detection after liquid-liquid extraction. Many pesticides were reactive via hydrolysis and/or chlorination and ozonation mechanisms under typical drinking water treatment conditions, with less reactivity exhibited on average for chlorine dioxide, monochloramine, hydrogen peroxide, and UV(254). The pyrazole and organophosphorous pesticides were most reactive in general, whereas carbamates and others were less reactive. The screening study provides guidance for the pesticide/oxidation systems that are most likely to lead to degradates in water treatment and the environment.

Choline dehydrogenase polymorphism rs12676 is a functional variation and is associated with changes in human sperm cell function.

Approximately 15% of couples are affected by infertility and up to half of these cases arise from male factor infertility. Unidentified genetic aberrations such as chromosomal deletions, translocations and single nucleotide polymorphisms (SNPs) may be the underlying cause of many cases of idiopathic male infertility. Deletion of the choline dehydrogenase (Chdh) gene in mice results in decreased male fertility due to diminished sperm motility; sperm from Chdh(-/-) males have decreased ATP concentrations likely stemming from abnormal sperm mitochondrial morphology and function in these cells. Several SNPs have been identified in the human CHDH gene that may result in altered CHDH enzymatic activity. rs12676 (G233T), a non-synonymous SNP located in the CHDH coding region, is associated with increased susceptibility to dietary choline deficiency and risk of breast cancer. We now report evidence that this SNP is also associated with altered sperm motility patterns and dysmorphic mitochondrial structure in sperm. Sperm produced by men who are GT or TT for rs12676 have 40% and 73% lower ATP concentrations, respectively, in their sperm. rs12676 is associated with decreased CHDH protein in sperm and hepatocytes. A second SNP located in the coding region of IL17BR, rs1025689, is linked to altered sperm motility characteristics and changes in choline metabolite concentrations in sperm.

Templating behavior of a long-chain ionic liquid in the hydrothermal synthesis of mesoporous silica.

The long-chain ionic liquid (IL) 1-hexadecyl-3-methylimidazolium chloride (C(16)mimCl) was used as a template to prepare porous silica with a two-dimensional hexagonal p6mm mesopore structure (MCM-41-type) as well as with a cubic Ia3d (gyroid, MCM-48-type structure) framework in basic synthesis medium via a hydrothermal synthesis procedure. A systematic study was carried out addressing the influence of the relative concentration of the IL and the pH on the mesostructure. As a main result, the IL template shows a broad range of conditions that allow the synthesis of the gyroid mesostructure with improved reproducibility. Unexpectedly, the formation of the hexagonal phase is less favorable, as the latter is quite sensitive to variations in parameters. This preference for the bicontinuous structure can be attributed to the special headgroup packing of ILs containing imidazolium groups.

Variations in dominant antigen determinants of glutaraldehyde polymerized human, bovine and porcine hemoglobin.

In this study, immunogenicity of human hemoglobin (hHb), bovine hemoglobin (bHb), porcine hemoglobin (pHb) and their glutaradehyde polymerized derivatives (hPolyHb, bPolyHb and bPolyHb, respectively) were compared. The nature of the dominant antigen determinants of the chemically polymerized proteins was studied. Glutaraldehyde chemical reaction enhanced the immunogenicity of the hemoglobin derivatives. In mice, the extent of the enhancement was largely comparable among hPolyHb, bPolyHb and pPolyHb. Using the methods of semi-quantitative western blotting and quantitative protein array, it was found that most of the polycloncal antibodies raised in rodents against glutaraldehyde polymerized hemoglobin derivatives of human, bovine or porcine species only weakly or did not cross-react with the hemoglobin derivatives of the other two species, indicating that hPolyHb, bPolyHb and bPolyHb vary significantly in their dominant antigen determinants, despite very high degree of identity in their primary amino acid sequences and high similarity in their three dimensional structures.

Atrophin-1-interacting protein 4/human Itch is a ubiquitin E3 ligase for human enhancer of filamentation 1 in transforming growth factor-beta signaling pathways.

Atrophin-1-interacting protein 4 (AIP4) is the human homolog of the mouse Itch protein (hItch), an E3 ligase for Notch and JunB. Human enhancer of filamentation 1 (HEF1) has been implicated in signaling pathways such as those mediated by integrin, T cell receptor, and B cell receptor and functions as a multidomain docking protein. Recent studies suggest that HEF1 is also involved in the transforming growth factor-beta (TGF-beta) signaling pathways, by interacting with Smad3, a key signal transducer downstream of the TGF-beta type I receptor. The interaction of Smad3 with HEF1 induces HEF1 proteasomal degradation, which was further enhanced by TGF-beta stimulation. The detailed molecular mechanisms of HEF1 degradation regulated by Smad3 were poorly understood. Here we report our studies that demonstrate the function of AIP4 as an ubiquitin E3 ligase for HEF1. AIP4 forms a complex with both Smad3 and HEF1 through its WW domains in a TGF-beta-independent manner and regulates HEF1 ubiquitination and degradation, which can be enhanced by TGF-beta stimulation. These findings reveal a new mechanism for Smad3-regulated proteasomal degradation events and also broaden the network of cross-talk between the TGF-beta signaling pathway and those involving HEF1 and AIP4.

Uncoupling of promitogenic and antiapoptotic functions of IL-2 by Smad-dependent TGF-beta signaling.

TGF-beta opposes proliferative signaling by IL-2 through mechanisms that remain incompletely defined. In a well-characterized CD8(+) T cell model using wild-type and mutated IL-2 receptors, we examined the effects of TGF-beta on distinct IL-2 signaling events in CD8(+) T cells. IL-2 induces c-myc, cyclin D2, and cyclin E in a redundant manner through the Shc and STAT5 pathways. TGF-beta inhibited the ability of either the Shc or STAT5 pathway to induce these genes, as well as T cell proliferation. The inhibitory effects of TGF-beta were reversed by expression of a dominant-negative form of Smad3. TGF-beta did not impair proximal signaling by Shc or STAT5, and induction of some downstream genes, including cytokine-inducible Src homology-2-containing protein (CIS), bcl-x(L), and bcl-2, was spared. Experiments with c-fos, cyclin D2, and CIS reporter genes revealed that promoter-proximal regulatory elements dictate the sensitivity of IL-2 target genes to inhibition by TGF-beta. By leaving the Shc and STAT5 pathways functional while inhibiting their target genes selectively, TGF-beta was found to uncouple the proliferative and antiapoptotic functions of IL-2. Thus, TGF-beta is not a simple antagonist of IL-2, but rather serves to qualitatively modify the IL-2 signal to create a unique pattern of gene expression that neither cytokine can induce independently.

SPARC regulates TGF-beta1-dependent signaling in primary glomerular mesangial cells.

Secreted protein acidic and rich in cysteine (SPARC), a member of the family of matricellular proteins, regulates the interaction of cells with pleiotropic factors and proteins of the extracellular matrix (ECM). Although it has been appreciated that transforming growth factor beta 1 (TGF-beta1) induces SPARC and collagen type I, we have recently shown that SPARC regulates the expression of TGF-beta1 and collagen type I in renal mesangial cells via a TGF-beta1-dependent pathway, and have proposed a reciprocal, autocrine regulatory feedback loop between SPARC and TGF-beta1. Herein, we sought to determine how SPARC regulates TGF-beta1-dependent signal transduction. Our data indicate that SPARC modulates the TGF-beta1-dependent phosphorylation of Smad-2 in primary mesangial cells derived from wild-type and SPARC-null mice. We also show that SPARC regulates the levels and activation of the stress-activated c-jun-N-terminal kinase (JNK) in mesangial cells by augmentation of the stimulatory effects of TGF-beta1. Furthermore, we found that SPARC increases the levels and the activity of the transcription factor c-jun. These effects of SPARC on the TGF-beta1 signaling pathway appear to be mediated through an interaction with the TGF-beta1-receptor complex, but only in the presence of TGF-beta1 bound to its cognate type II receptor. That SPARC is directly involved in the regulation of the TGF-beta1 signaling cascade is consistent with the paradigm that matricellular proteins modulate interactions among cells, growth factors, and their respective receptors.