12 research outputs found

    Continuous-Flow Monolithic Silica Microreactors with Arenesulphonic Acid Groups: Structure–Catalytic Activity Relationships

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    The performance of monolithic silica microreactors activated with sulphonic acid groups and a packed bed reactor with Amberlyst 15 resin were compared in the esterification of acetic acid with n-butanol. The monolithic microreactors were made of single silica rods with complex pore architecture, differing in the size of mesopores, and in particular, flow-through macropores which significantly affected the flow characteristic of the continuous system. The highest ester productivity of 105.2 mol·molH+−1·h−1 was achieved in microreactor M1 with the largest porosity, characterized by a total pore volume of 4 cm3·g−1, mesopores with 20 nm diameter, and large flow-through macropores 30–50 μm in size. The strong impact of the permeability of the monoliths on a reaction kinetics was shown

    Carbon monoliths as CO2 sorbents

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    W pracy przedstawiono wyniki badań nad syntezą monolitów węglowych. W syntezie zastosowano metodę twardego szablonowania a jako matrycę użyto monolitu krzemionkowego. Otrzymano monolity, które charakteryzowały się przepływową strukturą makroporów oraz rozbudowaną siecią mikro- i mezoporów. Zbadano wpływ prekursora węgla na właściwości strukturalne oraz sorpcyjne. Stwierdzono, że największą pojemność sorpcyjną wykazywały materiały otrzymane z rezorcyny oraz fenolu.The paper presents the results of study on the synthesis of carbon monoliths. The hard template method was used in the synthesis, where a silica monolith was applied as a structure scaffold. The obtained monoliths were characterized by a flow structure of macropores and an extensive network of micro and mesopores. The influence of the carbon precursor on the structural and sorption properties was investigated. It was found that the materials synthesized using resorcinol and phenol showed the highest sorption capacity

    Decreased Levels of Circulating Carboxylated Osteocalcin in Children with Low Energy Fractures:A Pilot Study

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    Objective: In the past decades, an increased interest in the roles of vitamin D and K has become evident, in particular in relation to bone health and prevention of bone fractures. The aim of the current study was to evaluate vitamin D and K status in children with low-energy fractures and in children without fractures. Methods: The study group of 20 children (14 boys, 6 girls) aged 5 to 15 years old, with radiologically confirmed low-energy fractures was compared with the control group of 19 healthy children (9 boys, 10 girls), aged 7 to 17 years old, without fractures. Total vitamin D (25(OH)D3 plus 25(OH)D2), calcium, BALP (bone alkaline phosphatase), NTx (N-terminal telopeptide), and uncarboxylated (ucOC) and carboxylated osteocalcin (cOC) serum concentrations were evaluated. Ratio of serum uncarboxylated osteocalcin to serum carboxylated osteocalcin ucOC:cOC (UCR) was used as an indicator of bone vitamin K status. Logistic regression models were created to establish UCR influence for odds ratio of low-energy fractures in both groups. Results: There were no statistically significant differences in the serum calcium, NTx, BALP, or total vitamin D levels between the two groups. There was, however, a statistically significant difference in the UCR ratio. The median UCR in the fracture group was 0.471 compared with the control group value of 0.245 (p < 0.0001). In the logistic regression analysis, odds ratio of low-energy fractures for UCR was calculated, with an increased risk of fractures by some 78.3 times. Conclusions: In this pilot study, better vitamin K status expressed as the ratio of ucOC:cOC-UCR—is positively and statistically significantly correlated with lower rate of low-energy fracture incidence

    Inactivation of epidermal growth factor by Porphyromonas gingivalis as a potential mechanism for periodontal tissue damage

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    Porphyromonas gingivalis is a Gram-negative bacterium associated with the development of periodontitis. The evolutionary success of this pathogen results directly from the presence of numerous virulence factors, including peptidylarginine deiminase (PPAD), an enzyme that converts arginine to citrulline in proteins and peptides. Such posttranslational modification is thought to affect the function of many different signaling molecules. Taking into account the importance of tissue remodeling and repair mechanisms for periodontal homeostasis, which are orchestrated by ligands of the epidermal growth factor receptor (EGFR), we investigated the ability of PPAD to distort cross talk between the epithelium and the epidermal growth factor (EGF) signaling pathway. We found that EGF preincubation with purified recombinant PPAD, or a wild-type strain of P. gingivalis, but not with a PPAD-deficient isogenic mutant, efficiently hindered the ability of the growth factor to stimulate epidermal cell proliferation and migration. In addition, PPAD abrogated EGFR-EGF interaction-dependent stimulation of expression of suppressor of cytokine signaling 3 and interferon regulatory factor 1. Biochemical analysis clearly showed that the PPAD-exerted effects on EGF activities were solely due to deimination of the C-terminal arginine. Interestingly, citrullination of two internal Arg residues with human endogenous peptidylarginine deiminases did not alter EFG function, arguing that the C-terminal arginine is essential for EGF biological activity. Cumulatively, these data suggest that the PPAD-activity-abrogating EGF function in gingival pockets may at least partially contribute to tissue damage and delayed healing within P. gingivalis-infected periodontia

    VItamin K In PEritonial DIAlysis (VIKIPEDIA):Rationale and study protocol for a randomized controlled trial

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    Vascular calcification (VC) is an active process, resulting from the disturbance of balance between inhibitors and promoters of calcification, in favor of the latter. Matrix Gla Protein, a powerful inhibitor of VC, needs vitamin K to become active. In vitamin K depletion, plasma levels of the inactive form of MGP, dephosphorylated, uncarboxylated MGP (dp-ucMGP) are increased and associated with VC and cardiovascular (CV) outcomes. End Stage Renal Disease (ESRD) patients have increased circulating dp-ucMGP levels and accelerated VC. VItamin K In PEritoneal DIAlysis (VIKIPEDIA) is a prospective, randomized, open label, placebo-controlled trial, evaluating the effect of vitamin K2 supplementation on arterial stiffness and CV events in ESRD patients undergoing peritoneal dialysis (PD). Forty-four PD patients will be included in the study. At baseline, dp-ucMGP and pulse-wave velocity (PWV) will be assessed and then patients will be randomized (1:1 ratio) to vitamin K (1000 μg MK-7/day) or placebo for 1.5 years. The primary endpoint of this trial is the change in PWV in the placebo group as compared to the treatment group. Secondary endpoints are the occurrence of CV events, mortality, changes in PD adequacy, change in 24-hour ambulatory blood pressure indexes and aortic systolic blood pressure and changes in calcium/phosphorus/parathormone metabolism. VIKIPEDIA is a new superiority randomized, open label, placebo-controlled trial aiming to determine the effect of vitamin K2 supplementation on VC, CV disease and calcium/phosphorus metabolism, in PD patients. Trial registration: The protocol of this study is registered at ClinicalTrials.gov with identification number NCT04900610 (25 May 2021)

    Aggravation of collagen-induced arthritis was specific to exposure to viable <i>P. gingivalis</i>.

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    <p>(A) Development of CIA at 5–6 weeks in DBA/1 mice (n = 7) were compared after exposure to viable <i>P. gingivalis</i> and heat-killed <i>P. gingivalis</i>; (B) Mice were immunized with <i>P. gingivalis</i> cell-envelope fractions (n = 10) 3 weeks prior to CII challenge and the development CIA were monitored at the 5–6 weeks period. (C) Mice were challenged with the periodontal pathogen <i>P. intermedia</i> strain 17 as compared to wild-type <i>P. gingivalis</i>. Points represent mean ± SEM. Two-way ANOVA with Bonferroni's post-test was used for the statistical evaluation (*** p<0.001, **** p<0.0001).</p

    Inoculation with <i>P. gingivalis</i> strain W83 leads to citrullination <i>in vivo</i> and, in turn, production of antibody against citrullinated proteins (aCCP).

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    <p>(A) Subcutaneously implanted titanium chambers were inoculated with: 1) 1×10<sup>8 </sup><i>P. gingivalis</i>, 2) PBS, 3) 5×10<sup>7</sup> and 4) 1×10<sup>7 </sup><i>P. gingivalis</i>. After 24 h, 20 µl of chamber fluid was collected and assayed for citrullinated proteins by immunoblotting with anti-modified citrulline antibody. B) Level of citrullinated proteins in chamber fluid 7 days post-inoculation. Pooled chamber fluid from 2 independent experiments was used. Horizontal bar and error bars represent the mean and SEM, respectively. C) Serum titers of aCCP IgG and D) IgG antibodies against CEP-1 were determined using an ELISA 45 days post-immunization with CII. Error bars represent the SEM. Statistical evaluation was carried out using one way ANOVA. * denotes p<0.05.</p

    Aggravation of collagen-induced arthritis in DBA/1 mice was dependent on the production of <i>P. gingivalis</i> peptidylarginine deiminase (PPAD).

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    <p><b><i> </i></b> Mice (n = 7) were inoculated with 1×10<sup>8</sup> CFU <i>P. gingivalis</i> wild-type strain W83 or PPAD-knockout strain (dPAD) and subsequently immunized with CII. (A) Kaplan-Meier plots displaying the clinical onset of arthritis (log-rank test, p = 0.002). (B) Mean severity of arthritis in mice followed for 5–6 weeks after immunization. (C) Histological signs of synovitis and (D) erosion on day 45 after CII immunization. (E) Scatter dot plot showing MPO activity in 1 g of joint tissue extract at day 45 after CII immunization. H&E staining of the representative inflamed tarsal joints from (F) CII- immunized DBA/1, (G) mice infected with wild-type <i>P. gingivalis</i> strain W83, and (H) isogenic dPAD mutant. Horizontal bar and error bars represent the mean and SEM, respectively. Statistical evaluation using two-way ANOVA with Bonferroni's post-test were employed for data in (B) and statistical differences between groups were analyzed using Mann-Whitney U test (C) or one way ANOVA (D). ** denotes p<0.01; ***, p<0.001; ****, p<0.0001.</p
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