297 research outputs found
Carbohydrate-carbohydrate interaction provides adhesion force and specificity for cellular recognition and adhesion
Carbohydrates at the cell surface have been proposed as mediators in cell-cell
recognition events involved in embryogenesis, metastasis, and other proliferation
processes by calcium-dependent carbohydrate to carbohydrate interactions. They are
the most prominently exposed structures on the surface of living cells, and with
flexible chains and many binding sites are ideal to serve as the major players in
initiating these cellular events. However, biological relevance of these type
interactions is often questioned because of the very low affinity binding of single
carbohydrate molecules and that they manifest themselves only through the contact
of a large number of molecules tightly arranged in the membrane. Weak interactions
are considerably more difficult to study and only a few biologically significant
examples of direct carbohydrate-carbohydrate interactions have been reported, e.g.
pioneering work showing glycosphingolipid self-interactions through multivalent
interaction of Lewis X epitopes. However, there are no reports on the existence of
specific proteoglycan self-interactions through carbohydrate-carbohydrate
interactions in cellular recognition system, as it has been done with
glycosphingolipids.
Here, we used sponges, organisms on which the first proteoglycan-mediated cell-cell
recognition in the animal kingdom was demonstrated, as a model system to study
carbohydrate-mediated cellular recognition. We show that the interaction between
single oligosaccharides from surface proteoglycans is relatively strong and
comparable to protein-carbohydrate interactions, highly specific, and dependent on
Ca2+-ions.
200 kDa glycans from the core protein of Microciona prolifera cell surface
proteoglycans have been previously shown to mediate homotypic Microciona proteoglycan-proteoglycan interactions. Here, 200 kDa glycans from four different
sponge species: Microciona prolifera, Halichondria panicea, Suberites fuscus and
Cliona celata were purified and investigated for species-specific interactions.
Selective recognition of glycans by live cells was studied to confirm the existence of
glycan-glycan recognition system in biologically relevant situations. Mature sponge
cells have the ability to reaggregate species-specifically and form homogenous
aggregates on a shaker at the right shear forces in the presence of physiological 10
mM Ca2+. Live cells were allowed to aggregate with glycan-coated beads similar in
size to small sponge cells in the presence of calcium. They specifically recognized
beads coated with their own glycans and did not mix but separated from beads
coated with glycans isolated from different species.
The glycan-glycan recognition assay was developed to mimic species-specific cellcell
recognition in sponges. 200 kDa glycans immobilized onto beads similar in size
to small sponge cells assembled species-specifically in the presence of physiological
calcium, at the same shear forces as in cell-cell aggregation. Glycans coated on
beads aggregated with glycans from the same species coated on beads, and separated
from glycans from other species. The glycan density necessary for specific live cellcell
recognition in sponges is 828 molecules/ÎĽm2. In our studies, the glycan density
necessary for specific glycan-coated bead was very similar: ~810 molecules/ÎĽm2.
Mature live cells demonstrated specific recognition of 200 kDa glycans during
selective-binding to glycans coated on surfaces in the presence of calcium. They
strongly adhered to glycans from their own surface proteoglycans coated onto a solid
polystyrene phase, while the binding to glycans from different proteoglycans was 3 -
5 times lower. Moreover, homotypic adhesion to glycan-coated plates enhanced
sponge cell differentiation and formation of mineral skeleton (spicules).
Larval cells, after settlement and spreading of larvae, can fuse species-specifically in
nature. In our studies, live larval cells recognized and adhered specifically to glycans purified from adhesion proteoglycans from their "mother sponge". They showed
almost no interaction with glycans from other species.
As in cell-glycan adhesion assays, highly species-specific adhesion of 200 kDa
glycans to glycan-coated surfaces could be observed in the presence of
physiological calcium. Tested glycans bound strongly to glycans from the same
species and showed up to a six fold reduction in binding to glycans from other
species.
Atomic force microscopy (AFM) was performed to measure for the first time
adhesion forces between single glycan molecules obtained from different surface
proteoglycans. Measurements revealed equally strong adhesion forces in the range of
several hundred piconewtons (pN) between glycan molecules as between proteins
and glycans measured in another recognition system. Moreover, statistically
significant differences (p value < 0.01) were seen between homotypic (glycans from
the same species) and heterotypic (glycans from different species) interactions.
Moreover, the polyvalent character of binding characterized mainly interactions
between glycans from the same species. This indicates that not only the higher
adhesion force per binding site as such but also the higher amount of multiple
interactions between glycans from the same species versus mixture of glycans from
different species guaranteed the specificity of the glycan-mediated recognition.
These findings confirm for the first time the existence of specific glycan-glycan
recognition system between cell surface proteoglycans. We propose that these cell's
outermost surface structures serve as important players in initiating the very first
contacts between cells through highly species-specific and flexible carbohydratecarbohydrate
interactions
Carbohydrate-carbohydrate interaction provides adhesion force and specificity for cellular recognition and adhesion
Carbohydrates at the cell surface have been proposed as mediators in cell-cell
recognition events involved in embryogenesis, metastasis, and other proliferation
processes by calcium-dependent carbohydrate to carbohydrate interactions. They are
the most prominently exposed structures on the surface of living cells, and with
flexible chains and many binding sites are ideal to serve as the major players in
initiating these cellular events. However, biological relevance of these type
interactions is often questioned because of the very low affinity binding of single
carbohydrate molecules and that they manifest themselves only through the contact
of a large number of molecules tightly arranged in the membrane. Weak interactions
are considerably more difficult to study and only a few biologically significant
examples of direct carbohydrate-carbohydrate interactions have been reported, e.g.
pioneering work showing glycosphingolipid self-interactions through multivalent
interaction of Lewis X epitopes. However, there are no reports on the existence of
specific proteoglycan self-interactions through carbohydrate-carbohydrate
interactions in cellular recognition system, as it has been done with
glycosphingolipids.
Here, we used sponges, organisms on which the first proteoglycan-mediated cell-cell
recognition in the animal kingdom was demonstrated, as a model system to study
carbohydrate-mediated cellular recognition. We show that the interaction between
single oligosaccharides from surface proteoglycans is relatively strong and
comparable to protein-carbohydrate interactions, highly specific, and dependent on
Ca2+-ions.
200 kDa glycans from the core protein of Microciona prolifera cell surface
proteoglycans have been previously shown to mediate homotypic Microciona proteoglycan-proteoglycan interactions. Here, 200 kDa glycans from four different
sponge species: Microciona prolifera, Halichondria panicea, Suberites fuscus and
Cliona celata were purified and investigated for species-specific interactions.
Selective recognition of glycans by live cells was studied to confirm the existence of
glycan-glycan recognition system in biologically relevant situations. Mature sponge
cells have the ability to reaggregate species-specifically and form homogenous
aggregates on a shaker at the right shear forces in the presence of physiological 10
mM Ca2+. Live cells were allowed to aggregate with glycan-coated beads similar in
size to small sponge cells in the presence of calcium. They specifically recognized
beads coated with their own glycans and did not mix but separated from beads
coated with glycans isolated from different species.
The glycan-glycan recognition assay was developed to mimic species-specific cellcell
recognition in sponges. 200 kDa glycans immobilized onto beads similar in size
to small sponge cells assembled species-specifically in the presence of physiological
calcium, at the same shear forces as in cell-cell aggregation. Glycans coated on
beads aggregated with glycans from the same species coated on beads, and separated
from glycans from other species. The glycan density necessary for specific live cellcell
recognition in sponges is 828 molecules/ÎĽm2. In our studies, the glycan density
necessary for specific glycan-coated bead was very similar: ~810 molecules/ÎĽm2.
Mature live cells demonstrated specific recognition of 200 kDa glycans during
selective-binding to glycans coated on surfaces in the presence of calcium. They
strongly adhered to glycans from their own surface proteoglycans coated onto a solid
polystyrene phase, while the binding to glycans from different proteoglycans was 3 -
5 times lower. Moreover, homotypic adhesion to glycan-coated plates enhanced
sponge cell differentiation and formation of mineral skeleton (spicules).
Larval cells, after settlement and spreading of larvae, can fuse species-specifically in
nature. In our studies, live larval cells recognized and adhered specifically to glycans purified from adhesion proteoglycans from their "mother sponge". They showed
almost no interaction with glycans from other species.
As in cell-glycan adhesion assays, highly species-specific adhesion of 200 kDa
glycans to glycan-coated surfaces could be observed in the presence of
physiological calcium. Tested glycans bound strongly to glycans from the same
species and showed up to a six fold reduction in binding to glycans from other
species.
Atomic force microscopy (AFM) was performed to measure for the first time
adhesion forces between single glycan molecules obtained from different surface
proteoglycans. Measurements revealed equally strong adhesion forces in the range of
several hundred piconewtons (pN) between glycan molecules as between proteins
and glycans measured in another recognition system. Moreover, statistically
significant differences (p value < 0.01) were seen between homotypic (glycans from
the same species) and heterotypic (glycans from different species) interactions.
Moreover, the polyvalent character of binding characterized mainly interactions
between glycans from the same species. This indicates that not only the higher
adhesion force per binding site as such but also the higher amount of multiple
interactions between glycans from the same species versus mixture of glycans from
different species guaranteed the specificity of the glycan-mediated recognition.
These findings confirm for the first time the existence of specific glycan-glycan
recognition system between cell surface proteoglycans. We propose that these cell's
outermost surface structures serve as important players in initiating the very first
contacts between cells through highly species-specific and flexible carbohydratecarbohydrate
interactions
Bibliografia pracowników naukowych Wydziału Prawa, Prawa Kanonicznego i Administracji Katolickiego Uniwersytetu Lubelskiego Jana Pawła II za rok 2017
Carbohydrate–carbohydrate interaction provides adhesion force and specificity for cellular recognition
© 2004 Bucior et al. This article is distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License. The definitive version was published in Journal of Cell Biology 165 (2004): 529-537, doi:10.1083/jcb.200309005.The adhesion force and specificity in the first experimental evidence for cell–cell recognition in the animal kingdom were assigned to marine sponge cell surface proteoglycans. However, the question whether the specificity resided in a protein or carbohydrate moiety could not yet be resolved. Here, the strength and species specificity of cell–cell recognition could be assigned to a direct carbohydrate–carbohydrate interaction. Atomic force microscopy measurements revealed equally strong adhesion forces between glycan molecules (190–310 piconewtons) as between proteins in antibody–antigen interactions (244 piconewtons). Quantitative measurements of adhesion forces between glycans from identical species versus glycans from different species confirmed the species specificity of the interaction. Glycan-coated beads aggregated according to their species of origin, i.e., the same way as live sponge cells did. Live cells also demonstrated species selective binding to glycans coated on surfaces. These findings confirm for the first time the existence of relatively strong and species-specific recognition between surface glycans, a process that may have significant implications in cellular recognition.This work was supported by the Friedrich Miescher Institute, branch of
the Novartis Research Foundation, the M.E. MĂĽller Foundation, and the
Swiss National Research Foundatio
Evaluating macrophytes as indicators of anthropogenic pressures in rivers in Ireland
Publication history: Accepted - 6 January 2021; Published online - 10 February 2021.The ability of macrophytes to indicate
pressures in rivers was assessed by comparing metrics
for nitrate (NO3), ammonia (NH4), soluble reactive
phosphorus (SRP), dissolved oxygen saturation (DO),
pH (PH) and siltation (SUBS) with direct estimates of
the pressures at 810 sites in the Republic of Ireland,
supplemented with General Linear Models (GLMs).
The bivariate and rank correlation coefficients using
the full data range and the first and fourth quartiles of
the river pressures varied between 0.22 and - 0.39 for
NO3 and DO; they were smaller or not significant for
the other four metrics. The GLMs provided evidence
for an independent association between NO3 and the
nitrate concentration and SUBS and ammonia,
indicating some specificity for these metrics. Discriminating
sites in the first and fourth quartiles produced
Type II errors between 37 (PH) and 69% (NH4), with a
mean of 50. As the pressure-impact relationships are
not precise enough (low correlation coefficients) that
evidence from a single macrophyte metric is reliable,
combining the metric with evidence from other
biological groups at one site or from three or more
sites may be the most useful approach.Environmental Protection Agency of Ireland - funding of the DETECT Project
(2015-W-LS-9)
Burnley Borough Council - funding to AB
Objazd naukowy Lublin –Warszawa–Poznań–Kórnik (16–20 kwietnia 2018) – sprawozdanie
The autonomy of public sector units in the process of formulating accounting policy : evidence from Poland
PURPOSE: To examine the autonomy of public sector entity in the development and
application of accounting policy, understood as a mandatory element of the accounting
system, and the perception of such independence on the part of the persons responsible for
accounting in these units.DESIGN/METHODOLOGY/APPROACH: The article adopts a qualitative research approach, in
accordance with the case study and survey method. The analysis incorporated data collected
during a case study carried out in two Polish budgetary units (basic form of public finance
sector units in Poland), the survey was completed by 35 intentionally selected entities.FINDINGS: The authors found that the entities surveyed show independence in the creation
and development of accounting policy and practice, however, this independence is
significantly limited by the interference of supervisors. At the same time, the survey shows
that the persons responsible for accounting in these entities consider it desirable to increase
their freedom in accounting policy development.PRACTICAL IMPLICATIONS: In their opinion, this will provide an opportunity to make the
accounting system a tool that is more useful in management.ORIGINALITY/VALUE: Examination of public-entity accounting policy is rare in general, and
virtually absent with respect to Polish entities. Thus, this work is a step to fill this research
gap. The article contributes to the literature on the subject by exploring the issue.peer-reviewe
Effectiveness and safety of betrixaban extended prophylaxis for venous thromboembolism compared with standard-duration prophylaxis intervention in acute medically ill patients : a systematic literature review and network meta-analysis
Aims: To determine the clinical effectiveness and safety of venous thromboembolism (VTE) prophylaxis using US- and Europe-approved anticoagulants relative to extended-duration VTE prophylaxis with betrixaban. Low molecular weight heparins (LMWHs), unfractionated heparin (UFH), fondaparinux sodium and placebo were each compared to betrixaban, as standard-duration VTE prophylaxis for hospitalized, non-surgical patients with acute medical illness at risk of VTE.
Materials and methods: A systematic literature review was conducted up to June 2019 to identify randomized controlled trials (RCTs) of VTE prophylaxis in hospitalized, non-surgical patients with acute medical illness at risk of VTE. Studies that reported the occurrence of VTE events (including death) and, where possible, major bleeding, from treatment initiation to 20–50 days thereafter were retrieved and extracted. A Bayesian fixed effect network meta-analysis was used to estimate efficacy and safety of betrixaban compared with standard-duration VTE prophylaxis.
Results: Seven RCTs were analyzed which compared betrixaban, LMWHs, UFH, fondaparinux sodium, or placebo. There were significantly higher odds (median odds [95% credible interval]) of VTE with LMWHs (1.38 [1.12–1.70]), UFH (1.60 [1.05–2.46]), and placebo (2.37 [1.55–3.66]) compared with betrixaban. There were significantly higher odds of VTE-related death with placebo (7.76 [2.14–34.40]) compared with betrixaban. No significant differences were observed for the odds of major bleeding with all comparators, VTE-related death with any active standard-duration VTE prophylaxis, or of VTE with fondaparinux sodium, compared with betrixaban.
Limitations and conclusions: In this indirect comparison, betrixaban was shown to be an effective regimen with relative benefits compared with LMWHs and UFH. This indicates that betrixaban could reduce the burden of VTE in at-risk hospitalized patients with acute medical illness who need extended prophylaxis, though without direct comparative evidence, stronger conclusions cannot be drawn
Machine learning using host/guest energy histograms to predict adsorption in metal–organic frameworks: Application to short alkanes and Xe/Kr mixtures
A machine learning (ML) methodology that uses a histogram of interaction energies has been applied to predict gas adsorption in metal–organic frameworks (MOFs) using results from atomistic grand canonical Monte Carlo (GCMC) simulations as training and test data. In this work, the method is first extended to binary mixtures of spherical species, in particular, Xe and Kr. In addition, it is shown that single-component adsorption of ethane and propane can be predicted in good agreement with GCMC simulation using a histogram of the adsorption energies felt by a methyl probe in conjunction with the random forest ML method. The results for propane can be improved by including a small number of MOF textural properties as descriptors. We also discuss the most significant features, which provides physical insight into the most beneficial adsorption energy sites for a given application
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