29 research outputs found
Critical percolation of free product of groups
In this article we study percolation on the Cayley graph of a free product of
groups.
The critical probability of a free product of groups
is found as a solution of an equation involving only the expected subcritical
cluster size of factor groups . For finite groups these
equations are polynomial and can be explicitly written down. The expected
subcritical cluster size of the free product is also found in terms of the
subcritical cluster sizes of the factors. In particular, we prove that
for the Cayley graph of the modular group (with the
standard generators) is , the unique root of the polynomial
in the interval .
In the case when groups can be "well approximated" by a sequence of
quotient groups, we show that the critical probabilities of the free product of
these approximations converge to the critical probability of
and the speed of convergence is exponential. Thus for residually finite groups,
for example, one can restrict oneself to the case when each free factor is
finite.
We show that the critical point, introduced by Schonmann,
of the free product is just the minimum of for the factors
Heat-Induced Structural Changes Affect OVA-Antigen Processing and Reduce Allergic Response in Mouse Model of Food Allergy
BACKGROUND AND AIMS: The egg protein ovalbumin (OVA) belongs to six most frequent food allergens. We investigated how thermal processing influences its ability to induce allergic symptoms and immune responses in mouse model of food allergy. METHODOLOGY/PRINCIPAL FINDINGS: Effect of increased temperature (70°C and 95°C) on OVA secondary structure was characterized by circular dichroism and by the kinetics of pepsin digestion with subsequent HPLC. BALB/c mice were sensitized intraperitoneally and challenged with repeated gavages of OVA or OVA heated to 70°C (h-OVA). Levels of allergen-specific serum antibodies were determined by ELISA (IgA and IgGs) or by β-hexosaminidase release test (IgE). Specific activities of digestive enzymes were determined in brush border membrane vesicles of jejunal enterocytes. Cytokine production and changes in regulatory T cells in mesenteric lymph nodes and spleen were assessed by ELISA and FACS. Heating of OVA to 70°C caused mild irreversible changes in secondary structure compared to boiling to 95°C (b-OVA), but both OVA treatments led to markedly different digestion kinetics and Tregs induction ability in vitro, compared to native OVA. Heating of OVA significantly decreased clinical symptoms (allergic diarrhea) and immune allergic response on the level of IgE, IL-4, IL-5, IL-13. Furthermore, h-OVA induced lower activities of serum mast cell protease-1 and enterocyte brush border membrane alkaline phosphatase as compared to native OVA. On the other hand h-OVA stimulated higher IgG2a in sera and IFN-γ secretion by splenocytes. CONCLUSIONS: Minor irreversible changes in OVA secondary structure caused by thermal processing changes both its digestion and antigenic epitopes formation, which leads to activation of different T cell subpopulations, induces shift towards Th1 response and ultimately reduces its allergenicity
Palaeoecological data indicates land-use changes across Europe linked to spatial heterogeneity in mortality during the Black Death pandemic
The Black Death (1347–1352 CE) is the most renowned pandemic in human history, believed by many to have killed half of Europe’s population. However, despite advances in ancient DNA research that conclusively identified the pandemic’s causative agent (bacterium Yersinia pestis), our knowledge of the Black Death remains limited, based primarily on qualitative remarks in medieval written sources available for some areas of Western Europe. Here, we remedy this situation by applying a pioneering new approach, ‘big data palaeoecology’, which, starting from palynological data, evaluates the scale of the Black Death’s mortality on a regional scale across Europe. We collected pollen data on landscape change from 261 radiocarbon-dated coring sites (lakes and wetlands) located across 19 modern-day European countries. We used two independent methods of analysis to evaluate whether the changes we see in the landscape at the time of the Black Death agree with the hypothesis that a large portion of the population, upwards of half, died within a few years in the 21 historical regions we studied. While we can confirm that the Black Death had a devastating impact in some regions, we found that it had negligible or no impact in others. These inter-regional differences in the Black Death’s mortality across Europe demonstrate the significance of cultural, ecological, economic, societal and climatic factors that mediated the dissemination and impact of the disease. The complex interplay of these factors, along with the historical ecology of plague, should be a focus of future research on historical pandemics.The authors acknowledge the following funding sources: Max Planck Independent Research Group, Palaeo-Science and History Group (A.I., A.M. and C.V.); Estonian Research Council #PRG323, PUT1173 (A.Pos., T.R., N.S. and S.V.); European Research Council #FP7 263735 (A.Bro. and A.Plu.), #MSC 655659 (A.E.); Georgetown Environmental Initiative (T.N.); Latvian Council of Science #LZP-2020/2-0060 (N.S. and N.J.); LLNL-JRNL-820941 (I.T.); NSF award #GSS-1228126 (S.M.); Polish-Swiss Research Programme #013/2010 CLIMPEAT (M.Lam.), #086/2010 CLIMPOL (A.W.); Polish Ministry of Science and Higher Education #N N306 275635 (M.K.); Polish National Science Centre #2019/03/X/ST10/00849 (M.Lam.), #2015/17/B/ST10/01656 (M.Lam.), #2015/17/B/ST10/03430 (M.Sło.), #2018/31/B/ST10/02498 (M.Sło.), #N N304 319636 (A.W.); SCIEX #12.286 (K.Mar.); Spanish Ministry of Economy and Competitiveness #REDISCO-HAR2017-88035-P (J.A.L.S.); Spanish Ministry of Education, Culture and Sports #FPU16/00676 (R.L.L.); Swedish Research Council #421-2010-1570 (P.L.), #2018-01272 (F.C.L. and A.S.); Volkswagen Foundation Freigeist Fellowship Dantean Anomaly (M.B.), Spanish Ministry of Science and Innovation #RTI2018-101714-B-I00 (F.A.S. and D.A.S.), OP RDE, MEYS project #CZ.02.1.01/0.0/0.0/16_019/0000728 (P.P.)Peer reviewe
Cisplatin induced gamma-glutamyltransferase up-regulation, hypertrophy and differentiation in astrocytic glioma cells in culture
Gamma-glutamyltransferase (GGT)
hydrolyses gamma-glutamylated peptides, including
glutathione and transports amino acids into the cells. The
enzyme is up-regulated in some tumors, especially those
with a higher degree of malignancy and resistance to
cytostatics. In this study we examined the effects of
Cisplatin (1.6 x 10-5M) on the activity of GGT in
astrocytic C6 glioma cells in cultures monitored for
growth, morphology and differentiation. Initially (24 h),
the drug inhibited cell division and later (96 h), it caused
apoptotic death of about half of the population. The
more resistant and surviving cells became hypertrophic
and more differentiated, as indicated by their larger size
and higher protein content, including the maturationspecific
GFAP. In addition, the activity of GGT was
significantly elevated in these cells at 48 h and onwards.
At 96 h, the biochemically determined enzyme activity
was between 230% and 330% above the controls.
Compared to the protein content, the GGT activity
started to increase later (48 h) but it grew steeper
towards 72-96 h. Similarly, histochemical analysis
revealed a manifold increase in the number of GGT+
cells in the population and higher intensity of staining
per cell from at 48 h and onwards. The study showed
that the transformed astrocytic cells can up-regulate
GGT activity as part of an adaptation and/or, survivalenhancing
reaction triggered by Cisplatin
Differences in attitudes to ethic aspects of end of life care among patients with progressive neurological diseases and their family members
Palynology research of water reservoirs of later mediaeval and post-mediaeval deserted villages in West Bohemia, Czech Republic
This paper presents palynological research of sediments in artificial water reservoirs from deserted later mediaeval villages in the Pilsen Region, Czech Republic. Coring and test-pitting of these features have shown that in some cases, their preserved fills are formed by wet sediments providing the ideal conditions for paleoecological record. Pollen profile analysis from four sites has allowed us to reconstruct the natural environment of mediaeval villages in order to asses land use and human impact on vegetation. Pollen data also recorded forest succession following the desertion of the settlement, vegetation succession and changes in forest management in the Modern Era based on spruce cultivation. In one case, the pollen profile reflects the subsequent reestablishment of the village in the post-mediaeval period and its final abandonment during the Thirty Years’ War
Initial characterization of human DHRS1 (SDR19C1), a member of the short chain dehydrogenase/reductase superfamily.
Many enzymes from the short-chain dehydrogenase/reductase superfamily (SDR) have already been well characterized, particularly those that participate in crucial biochemical reactions in the human body (e.g. 11 beta-hydroxysteroid dehydrogenase 1, 17 beta-hydroxysteroid dehydrogenase 1 or carbonyl reductase 1). Several other SDR enzymes are completely or almost completely uncharacterized, such as DHRS1 (also known as SDR19C1). Based on our in silico and experimental approaches, DHRS1 is described as a likely monotopic protein that interacts with the membrane of the endoplasmic reticulum. The highest expression level of DHRS1 protein was observed in human liver and adrenals. The recombinant form of DHRS1 was purified using the detergent ndodecy1-beta-D-maltoside, and DHRS1 was proven to be an NADPH-dependent reductase that is able to catalyse the in vitro reductive conversion of some steroids (estrone, androstene-3,17-dione and cortisone), as well as other endogenous substances and xenobiotics. The expression pattern and enzyme activities fit to a role in steroid and/or xenobiotic metabolism; however, more research is needed to fully clarify the exact biological function of DHRS1
Late Glacial and Holocene sequences in rockshelters and adjacent wetlands of Northern Bohemia, Czech Republic: Correlation of environmental and archaeological records
This paper combines complex archaeological records from excavations of sandstone rockshelters with paleobotanical investigations in the adjacent wetlands of Northern Bohemia, Czech Republic. Several pollen diagramms from nearby peatbogs are used to document the paleoenvironmental development from the Late Glacial to the Middle Holocene. In addition, two recently excavated key archaeological sections were selected to document human behavioral responses to the climatic development: Kostelní rokle, and Smolný kámen. This region remained mostly unsettled during the Upper Paleolithic (Magdalenian or Epigravettian) so that the Late Paleolithic colonization after the LGM appears to be a major behavioral adaptation. The Early and Middle Mesolithic foragers developed this pattern to be optimally adapted to the versatile landscape of sandstone plateaus and canyons during the Holocene. The aim was to exploit its changing vegetational, aquatic and terrestric faunal resources, until the Late Mesolithic