110 research outputs found
Evolution of the bancassurance concept: banking and insurance associations
This article intends to discuss the determinants of the evolution of banking-insurance relations in the global dimension.The simultaneous complementarity and substitutability of the offer of banking and insurance services in businesspractice led to a tendency to integrate the activities of banks and insurance companies in search of new distributionchannels, such as bancassurance. Hence, the aim of the article is an attempt to present the genesis, historical adaptation,definition, and the essence of the bancassurance concept. The basic question that guides the considerations hererelates to the symmetry of development, namely: has the phenomenon of integration of financial institutions under thebancassurance concept developed at the same pace and adopted the same paradigm in each country? To achieve thisgoal, the literature on the subject and intranet resources from the canon of the financial market were used. The backgroundof the analysis is the experience of countries around the world where the idea of banking and insurance interactionswas found.Moreover, the article discusses the determinants, models, and forms of bancassurance, as well as indicates the epicenterof its practices and presents the phases (periods) of its development. Moreover, the problem of the lack of uniformand commonly used in the literature on the subject as well as in the economic practice of defining the concepts of bankingand insurance connections was analyzed
Use of a charge reducing agent to enable intact mass analysis of cysteine-linked antibody-drug-conjugates by native mass spectrometry
AbstractAntibody-drug-conjugates (ADC) are a growing class of anticancer biopharmaceuticals. Conjugation of cysteine linked ADCs, requires initial reduction of mAb inter-chain disulfide bonds, as the drugs are attached via thiol chemistry. This results in the active mAb moiety being transformed from a covalently linked tetramer to non-covalently linked complexes, which hinders precise determination of drug load with LC–MS. Here, we show how the addition of the charge reducing agent triethylammonium acetate (TEAA) preserves the intact mAb structure, is well suited to the study of cysteine linked conjugates and facilitates easy drug load determination by direct infusion native MS
Investigation of large protein and multimeric protein complex structures with mass spectrometry techniques
The biophysical properties, biological activity and function of macromolecular systems
are highly dependent on their structure. Structure-activity relationships of proteins and
their binding partners are critical for drug discovery, biochemical and medical research.
While the gas-phase environment might present as an unusual venue from which to
explore protein structure, for over the past two decades, nano-electrospray ionization
(nESI) coupled to mass spectrometry (MS) has been recognized as having great potential
for analysis of protein structure and protein non-covalent complexes. In conjunction
with related technique of ion mobility (IM), mass spectrometry (IM-MS) provides
insights into protein native-like conformations and any structural changes in may
undergo upon ligand binding or alternations induced via physical parameters such as
temperature, pressure or solution conditions. As most proteins tend to exist as multiple
domains; from the distribution of oligomeric states in the Protein Data Base (PDB) 86%
of proteins exist as oligomers; the work presented in this thesis focuses on application of
MS techniques to probe the tertiary and quaternary structure of various large and
multimeric protein complexes, their dynamics and/or conformational changes. Wherever
relevant, the gas-phase studies reported here are complemented by other techniques, such
as hydrogen deuterium exchange MS (HDX), molecular modelling (MD) and analytical
ultracentrifugation (AUC).
Firstly, the dynamics of intact monoclonal antibodies (mAbs) and their fragments are
explored with IM-MS. Variations observed in conformational landscapes occupied by
two mAb isotypes are rationalized by differences in disulfide linkages and non-covalent
interactions between the antibody peptide chains. Moreover, mAb intrinsic flexibility is
compared to other multimeric protein complexes in terms of collision cross section
distribution span. Secondly, variable temperature MS (VT-MS) and variable
temperature IM-MS (IM-MS) are used to probe unfolding and dissociation of four
standard multimeric protein complexes (TTR, avidin, conA and SAP) as a function of
the of analysis environment temperature. VT-MS is found to allow for decoupling of
their melting temperature (Tm) from the protein complex dissociation temperature (TGPD).
Whereas, VT-IM-MS is used to investigate structural changes of these protein
complexes at elevated temperatures and provide insights into the thermally induced
dissociation (TID) mechanism, as well as strength of the non-covalent interactions
between subunits. Thirdly, VT-(IM)-MS methodology is applied to study behaviour of
three mAbs: IgG1, IgG4 and an engineered IgG4 of increased thermal stability. Such
analysis shows to be promising for comparative thermal stability studies for proteins of
therapeutic interest. Lastly, the structure of ATP-phosphoribosyltransferase (MtATPPRT),
an enzyme catalysing the first step of the biosynthesis of L-histidine in
Mycobacterium tuberculosis, is explored. Conformational changes occurring upon
feedback allosteric inhibition by L-histidine are probed with MS, IM-MS, HDX-MS and
AUC. Reported results serve as the basis for IM-MS/HDX-MS based screening method
to be used for screening of a library of novel and promising anti-tuberculosis agents
Student jako weryfikator jakości usługi edukacyjnej oferowanej przez polskie uczelnie wyższe. Wyniki badań wstępnych
Celem artykułu jest próba znalezienia odpowiedzi na pytanie: jaki jest poziom zadowolenia studentów z jakości usługi edukacyjnej w ramach kształcenia akademickiego, a także sprawdzenie, czy istnieją istotne statystycznie zależności pomiędzy obszarami determinującymi jakość tej usługi a czynnikami opisującymi cechy respondentów. Analizę i opis oparto na badaniach przeprowadzonych wśród studentów zarządzania w różnych ośrodkach akademickich na terenie Polski. W badaniu ankietowym zastosowano wskaźnik satysfakcji klienta i wykazano, że istnieje niedomiar jakości, a najważniejszymi obszarami determinującymi jakość są: szybkość i niezawodność. Kolejna część badania dotycząca analizy współzależności wykazała, że każdy z badanych i analizowanych obszarów jakości usługi został co najmniej cztery razy zróżnicowany w odniesieniu do wszystkich z badanych zmiennych
Tandem Mass Spectrometric Analysis of Novel Peptide-Modified Gemini Surfactants Used as Gene Delivery Vectors.
NSERC, CIHR, CFIDiquaternary ammonium gemini surfactants have emerged as effective gene delivery vectors. A novel series of 11 peptide-modified compounds was synthesized, showing promising results in delivering genetic materials. The purpose of this work is to elucidate the tandem mass spectrometric (MS/MS) dissociation behavior of these novel molecules establishing a generalized MS/MS fingerprint. Exact mass measurements were achieved using a hybrid quadrupole orthogonal time-of-flight mass spectrometer, and a multi-stage MS/MS analysis was conducted using a triple quadrupole-linear ion trap mass spectrometer. Both instruments were operated in the positive ionization mode and are equipped with electrospray ionization. Abundant triply charged [M+H]3+ species were observed in the single-stage analysis of all the evaluated compounds with mass accuracies of less than 8 ppm in mass error. MS/MS analysis showed that the evaluated gemini surfactants exhibited peptide-related dissociation characteristics because of the presence of amino acids within the compounds' spacer region. In particular, diagnostic product ions were originated from the neutral loss of ammonia from the amino acids' side chain resulting in the formation of pipecolic acid at the N-terminus part of the gemini surfactants. In addition, a charge-directed amide bond cleavage was initiated by the amino acids' side chain producing a protonated α-amino-ε-caprolactam ion and its complimentary C-terminus ion that contains quaternary amines. MS/MS and MS3 analysis revealed common fragmentation behavior among all tested compounds, resulting in the production of a universal MS/MS fragmentation pathway
Interfacing low-energy SAW nebulization with liquid chromatography-mass spectrometry for the analysis of biological samples
Soft ionization methods for the introduction of labile biomolecules into a mass spectrometer are of fundamental importance to biomolecular analysis. Previously, electrospray ionization (ESI) and matrix assisted laser desorption-ionization (MALDI) have been the main ionization methods used. Surface acoustic wave nebulization (SAWN) is a new technique that has been demonstrated to deposit less energy into ions upon ion formation and transfer for detection than other methods for sample introduction into a mass spectrometer (MS). Here we report the optimization and use of SAWN as a nebulization technique for the introduction of samples from a low flow of liquid, and the interfacing of SAWN with liquid chromatographic separation (LC) for the analysis of a protein digest. This demonstrates that SAWN can be a viable, low-energy alternative to ESI for the LC-MS analysis of proteomic samples
Mechanisms of iron- and O2-sensing by the [4Fe-4S] cluster of the global iron regulator RirA
RirA is a global regulator of iron homeostasis in Rhizobium and related α-proteobacteria. In its [4Fe-4S] cluster-bound form it represses iron uptake by binding to IRO Box sequences upstream of RirA-regulated genes. Under low iron and/or aerobic conditions, [4Fe-4S] RirA undergoes cluster conversion/degradation to apo-RirA, which can no longer bind IRO Box sequences. Here, we apply time-resolved mass spectrometry and electron paramagnetic resonance spectroscopy to determine how the RirA cluster senses iron and O2. The data indicate that the key iron-sensing step is the O2-independent, reversible dissociation of Fe2+ from [4Fe-4S]2+ to form [3Fe-4S]0. The dissociation constant for this process was determined as Kd = ~3 µM, which is consistent with the sensing of ‘free’ iron in the cytoplasm. O2-sensing occurs through enhanced cluster degradation under aerobic conditions, via O2-mediated oxidation of the [3Fe-4S]0 intermediate to form [3Fe-4S]1+. This work provides a detailed mechanistic/functional view of an iron-responsive regulator
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Structure-functional changes in eNAMPT at high concentrations mediate mouse and human beta- cell dysfunction in type 2 diabetes
Aims/hypothesis
Progressive decline in functional beta cell mass is central to the development of type 2 diabetes. Elevated serum levels of extracellular nicotinamide phosphoribosyltransferase (eNAMPT) are associated with beta cell failure in type 2 diabetes and eNAMPT immuno-neutralisation improves glucose tolerance in mouse models of diabetes. Despite this, the effects of eNAMPT on functional beta cell mass are poorly elucidated, with some studies having separately reported beta cell-protective effects of eNAMPT. eNAMPT exists in structurally and functionally distinct monomeric and dimeric forms. Dimerisation is essential for the NAD-biosynthetic capacity of NAMPT. Monomeric eNAMPT does not possess NAD-biosynthetic capacity and may exert distinct NAD-independent effects. This study aimed to fully characterise the structure-functional effects of eNAMPT on pancreatic beta cell functional mass and to relate these to beta cell failure in type 2 diabetes.
Methods
CD-1 mice and serum from obese humans who were without diabetes, with impaired fasting glucose (IFG) or with type 2 diabetes (from the Body Fat, Surgery and Hormone [BodyFatS&H] study) or with or at risk of developing type 2 diabetes (from the VaSera trial) were used in this study. We generated recombinant wild-type and monomeric eNAMPT to explore the effects of eNAMPT on functional beta cell mass in isolated mouse and human islets. Beta cell function was determined by static and dynamic insulin secretion and intracellular calcium microfluorimetry. NAD-biosynthetic capacity of eNAMPT was assessed by colorimetric and fluorescent assays and by native mass spectrometry. Islet cell number was determined by immunohistochemical staining for insulin, glucagon and somatostatin, with islet apoptosis determined by caspase 3/7 activity. Markers of inflammation and beta cell identity were determined by quantitative reverse transcription PCR. Total, monomeric and dimeric eNAMPT and nicotinamide mononucleotide (NMN) were evaluated by ELISA, western blot and fluorometric assay using serum from non-diabetic, glucose intolerant and type 2 diabetic individuals.
Results
eNAMPT exerts bimodal and concentration- and structure-functional-dependent effects on beta cell functional mass. At low physiological concentrations (~1 ng/ml), as seen in serum from humans without diabetes, eNAMPT enhances beta cell function through NAD-dependent mechanisms, consistent with eNAMPT being present as a dimer. However, as eNAMPT concentrations rise to ~5 ng/ml, as in type 2 diabetes, eNAMPT begins to adopt a monomeric form and mediates beta cell dysfunction, reduced beta cell identity and number, increased alpha cell number and increased apoptosis, through NAD-independent proinflammatory mechanisms.
Conclusions/interpretation
We have characterised a novel mechanism of beta cell dysfunction in type 2 diabetes. At low physiological levels, eNAMPT exists in dimer form and maintains beta cell function and identity through NAD-dependent mechanisms. However, as eNAMPT levels rise, as in type 2 diabetes, structure-functional changes occur resulting in marked elevation of monomeric eNAMPT, which induces a diabetic phenotype in pancreatic islets. Strategies to selectively target monomeric eNAMPT could represent promising therapeutic strategies for the treatment of type 2 diabetes
Desalting large protein complexes during native electrospray mass spectrometry by addition of amino acids to the working solution.
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