Evaluation and comparison of structurally different cellulose-based hemostatic agents in a rat kidney model

Different topical hemostatic materials are used to achieve effective hemostasis. High hemostatic activity, biocompatibility, bioresorbability, and easy manipulation are to be expected in such a developed product. In the surgical world with these specific requirements, finding a proper hemostatic agent is very difficult. The study compared several materials of various construction properties, which were assessed for structural and related properties by morphological analyses and assessed in vivo for their efficiency and behaviour using a model of rat partial nephrectomy. New sodium salt of carboxymethyl cellulose (CMC) sponge with the lowest porosity and free swell absorptive capacity contained the highest amount of hydroxyl and carboxyl groups. Results revealed that this CMC material in the form of a bioresorbable sponge may ensure the necessary hemostatic effects, while also providing a positive influence on the reaction of the local tissue. The CMC material also needed significantly less time to achieve hemostasis (p?<?0.001). Moreover, the sponge reached satisfactory results in the histopathological evaluation with the lowest destruction score and favorable healing reaction. This modified product proved itself to be a promising bioresorbable hemostat, which, according to its design, matches with its surgical applications. In general, the obtained data elucidated the dependency of the total effect on its structure and composition.

Graphic abstract

     

Optimal labelling of a product of two paths

If G is a graph with p vertices and at least one edge, we set φ (G) = m n max |f(u) ? f(v)|, where the maximum is taken over all edges uv and the minimum over all one-to-one mappings f : V(G) → {1, 2, …, p}: V(G) denotes the set of vertices of G.P_n will denote a path of length n whose vertices are integers 1, 2, …, n with i adjacent to j if and only if |i ? j| = 1. P_m × P_n will denote a graph whose vertices are elements of {1, 2, …, m} × {1, 2, …, n} and in which (i, j), (r, s) are adjacent whenever either i = r and |j ? s| = 1 or j = s and |i ? r| = 1.Theorem.If max(m, n) ? 2, thenφ(P_m × P_n) = min(m, n).     

On a characterization of lattices by the betweenness relation —on a problem of M. Kolibiar

Presented by R. Quackenbush.     

Chromophoric binaphthyl derivatives

A short synthetic route is outlined, starting from bromo-BN derivatives, via halogen lithium exchange, subsequent Michael reaction with dimethylaminoacrolein, hydrolysis to the corresponding aldehyde, and final condensation with a benzothiazolium unit to produce a BN-pentamethinium system, which absorbs in the visible range around 450 nm. Enantiopure ligands show a decent Cotton effect in the CD spectrum. Preliminary data show potential of these compounds in the area of supramolecular chemistry (enantioselective recognition) and also for medicinal application (induction of apoptosis). [reaction: see text]     

Dithizone extraction of methylmercury,ethylmercury and phenylmercury

The distribution of methylmercury, ethylmercury and phenylmercury species between aqueous phases and pure carbon tetrachloride or dithizone solutions in carbon tetrachloride has been studied in detail. The stability constants of the chloride complexes and the extraction constants are reported. The influence of 16 masking agents at various pH values has been investigated; the distribution data found experimentally are compared with the calculated results.     

In-Vivo Analysis and Model-Based Prediction of Tensides’ Influence on Drug Absorption

Depending on their concentrations the surface-active substances, tensides (surfactants) can positively or negatively influence the drug absorption, which is widely used in the design of the dosage forms with controlled release. A problem is that the (in-vivo) rate of absorption cannot be directly measured and for that reason, it is frequently substituted by evaluation of the (in-vitro) dissolution. On other hand, a suitably designed pharmacokinetic model can directly predict virtually all pharmacokinetic quantities including both the rate of absorption and fraction of the dose reaching the blood circulation. The paper presents a new approach to the analysis of the rate of drug absorption and shows its superiority over traditional in-vivo approaches. Both the in-vivo analysis and model-based prediction of the tenside (monolaurin of sucrose) influence on the rate of absorption of the drug (sulfathiazole) after instantaneous per-oral administration to rats are discussed. It was found that 0.001% solution of tenside can increase the rate of absorption by cca 50% and a two-fold increase in absolute bioavailability can be reached. Attention is also devoted to the formal requirements laid on the model’s structure and its identifiability. The systematic design, substantiation and validation of a parsimonious predictive model that confirms in-vivo results are presented. The match between in-vivo observations and model-based predictions is demonstrated. The frequently overlooked metaphysics lying behind the compartmental modelling is briefly explained.     

Determination of arsenic by cathodic stripping voltammetry at a hanging mercury drop electrode

Arsenic (III), respectively arsenic(V) after the reduction were determined in model solutions and some inorganic and organic materials by fast scan differential pulse cathodic stripping voltammetry and by direct current cathodic stripping voltammetry with a rapid increase of potential. The accumulation on a hanging mercury drop electrode followed by cathodic stripping was carried out in 0.7–0.8M HCl or 1–2M H₂SO₄ solutions containing Cu(II)-ions. Detection limits calculated from regression parameters was determined to be under 1 ng/ml for the samples containing very low arsenic concentrations. The relative standard deviation did not reach 8% for arsenic contents about of 5 ng/ml.     

Chitinase Chit62J4 Essential for Chitin Processing by Human Microbiome Bacterium Clostridium paraputrificum J4

Commensal bacterium Clostridium paraputrificum J4 produces several extracellular chitinolytic enzymes including a 62 kDa chitinase Chit62J4 active toward 4-nitrophenyl N,N′-diacetyl-β-d-chitobioside (pNGG). We characterized the crude enzyme from bacterial culture fluid, recombinant enzyme rChit62J4, and its catalytic domain rChit62J4cat. This major chitinase, securing nutrition of the bacterium in the human intestinal tract when supplied with chitin, has a pH optimum of 5.5 and processes pNGG with K_m = 0.24 mM and k_cat = 30.0 s⁻¹. Sequence comparison of the amino acid sequence of Chit62J4, determined during bacterial genome sequencing, characterizes the enzyme as a family 18 glycosyl hydrolase with a four-domain structure. The catalytic domain has the typical TIM barrel structure and the accessory domains—2x Fn3/Big3 and a carbohydrate binding module—that likely supports enzyme activity on chitin fibers. The catalytic domain is highly homologous to a single-domain chitinase of Bacillus cereus NCTU2. However, the catalytic profiles significantly differ between the two enzymes despite almost identical catalytic sites. The shift of pI and pH optimum of the commensal enzyme toward acidic values compared to the soil bacterium is the likely environmental adaptation that provides C. paraputrificum J4 a competitive advantage over other commensal bacteria.