Efficient domination in knights graphs

The influence of a vertex set S ⊆V(G) is I(S) = Σv∈S(1 + deg(v)) = Σv∈S |N[v]|, which is the total amount of domination done by the vertices in S. The efficient domination number F(G) of a graph G is equal to the maximum influence of a packing, that is, F(G) is the maximum number of vertices one can dominate under the restriction that no vertex gets dominated more than once. In this paper, we consider the efficient domination number of some finite and infinite knights chessboard graphs

Queen\u27s domination using border squares and (\u3ci\u3eA\u3c/i\u3e,\u3ci\u3eB\u3c/i\u3e)-restricted domination

In this paper we introduce a variant on the long studied, highly entertaining, and very difficult problem of determining the domination number of the queen\u27s chessboard graph, that is, determining how few queens are needed to protect all of the squares of a k by k chessboard. Motivated by the problem of minimum redundance domination, we consider the problem of determining how few queens restricted to squares on the border can be used to protect the entire chessboard. We give exact values of border-queens required for the k by k chessboard when 1≤k≤13. For the general case, we present a lower bound of k(2-9/2k-√(8k2-49k+49)/2k) and an upper bound of k-2. For k=3t+1 we improve the upper bound to 2t+1 if 3t+1 is odd and 2t if 3t+1 is even. We generalize this problem to (A,B)-restricted parameters for vertex subsets A and B of V(G) where, for example, one must use only vertices in A to dominate all of B. Defining upper and lower parameters for independence, domination, and irredundance, we present a generalization of the domination chain of inequalities relating these parameters

Antiherpes simplex virus type 2 activity of the antimicrobial peptide subtilosin

In the present study we evaluated the antiviral activity of subtilosin, a cyclical peptide isolated from Bacillus amyloliquefaciens, against herpes simplex virus type 2 (HSV-2) in cell cultures and we investigated subtilosin mode of action. We determined, using a virus yield inhibition assay, that non cytotoxic concentrations of subtilosin inhibit HSV-2 replication in Vero cell cultures. Subtilosin strongly inhibited extracellular and total virus production even when it was added at 8 h post-infection indicating that not only virus release but also viral particle formation is impeded by the antiviral peptide. Although viral glycoprotein gD level of expression is not affected by the bacteriocin, an altered pattern of gD intracellular localization was detected by immunofluorescence assay in subtilosin treated culture. On the other hand, at high concentrations subtilosin displays virucidal action.Fil: Quintana, Verónica Mara. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Virología; ArgentinaFil: Torres, Nicolás. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Wachsman, Mónica B.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Virología; ArgentinaFil: Sinko, Patrick J.. State University of New Jersey; Estados UnidosFil: Castilla, Viviana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Virología; ArgentinaFil: Chikindas, Michael. State University of New Jersey; Estados Unido

The graph distance game

In the graph distance game, two players alternate in constructing a maximal path. The objective function is the distance between the two endpoints of the path, which one player tries to maximize and the other tries to minimize. In this note, we examine the distance game for various graphs, and provide general bounds, exact results for special graphs, and an algorithm for trees. Computer calculations suggest interesting conjectures for grids

A comparative study of the in vitro permeation of ibuprofen in mammalian skin, the PAMPA model and silicone membrane

Human skin remains the membrane of choice when conducting in vitro studies to determine dermal penetration of active pharmaceutical ingredients or xenobiotics. However there are ethical and safety issues associated with obtaining human tissue. For these reasons synthetic membranes, cell culture models or in silico predictive algorithms have been researched intensively as alternative approaches to predict dermal exposure in man. Porcine skin has also been recommended as an acceptable surrogate for topical or transdermal delivery research. Here we examine the in vitro permeation of a model active, ibuprofen, using human or porcine skin, as well as the Parallel Artificial Membrane Permeation Assay (PAMPA) model and silicone membrane. Finite dose studies were conducted in all models using commercial ibuprofen formulations and simple volatile ibuprofen solutions. The dose applied in the PAMPA model was also varied in order to determine the amount of applied formulation which best simulates typical amounts of topical products applied by patients or consumers. Permeation studies were conducted up to 6 h for PAMPA and silicone and up to 48 h for human and porcine skin. Cumulative amounts permeated at 6 h were comparable for PAMPA and silicone, ranging from 91–136 g/cm2 across the range of formulations studied. At 48 h, maximum ibuprofen permeation in human skin ranged from 11–38 g/cm2 and corresponding values in porcine skin were 59–81 g/cm2. A dose of 1 l/cm2 was confirmed as appropriate for finite dose studies in the PAMPA model. The formulation which delivered the greatest amount of ibuprofen in human skin was also significantly more efficient than other formulations when evaluated in the PAMPA model. The PAMPA model also discriminated between different formulation types (i.e. gel versus solution) compared with other models. Overall, the results confirm the more permeable nature of the PAMPA, silicone membrane and porcine tissue models to ibuprofen compared with human skin. Further finite dose studies to elucidate the effects of individual excipients on the barrier properties of the PAMPA model are needed to expand the applications of this model. The range of actives that are suitable for study using the model also needs to be delineated

Estimating human drug oral absorption kinetics from Caco-2 permeability using an absorptiondisposition model: model development and evaluation and derivation of analytical solutions for k (a) and F (a).

ABSTRACT Intestinal transcellular permeability (P m ), measured across cell lines such as Caco-2 cells in vitro, is often used for assessing oral drug absorption potential in humans. However, the quantitative link between in vitro permeability and apparent in vivo absorption kinetics, based on drug appearance in plasma, is poorly understood. In the current study, a novel absorptiondisposition kinetic model that links traditional pharmacokinetic and mass transfer models was developed. Analytical solutions of k a and F a were deduced, and using Caco-2 permeability, F a in humans was predicted for 51 structurally diverse compounds. Predicted F a values were similar to and correlated highly with their corresponding experimental values with an average error of 1.88 Ϯ 1.06% (Ϫ17 to 22%) and r 2 ϭ 0.934. Simulated concentration profiles for 17 of 18 drugs corresponded to observed plasma concentration profiles in healthy volunteers. The equilibrium solution for k a (k a,eq ) was found to be a key determinant of F a , whereas under sink conditions, k a is likely to be a determinant of plasma concentration kinetics. The current version of the model offers a quantitative approach for predicting human oral absorption kinetics from in vitro permeability. It also establishes, for the first time, a quantitative link between P m and k a and between k a,eq and F a . This will facilitate better in vitro or in situ-in vivo correlations since it establishes a basis for incorporating permeability coefficients from the various experimental formats based on drug loss or appearance that are commonly used in the laboratory for permeability determination. Oral administration is the most commonly used drug-dosing route. Therefore, the ability to predict the rate and extent of absorption of drug candidates after oral administration is crucial during the preclinical phase of development. Such knowledge complements high throughput drug screening and allows scientists to select the best drug candidates early in the drug development cycle. Drug absorption from the gastrointestinal (GI) tract is affected by many factors. Besides the physiological conditions of the GI tract (e.g., absorptive surface area, local pH, food effects, intestinal transit time, and passive intestinal permeability) and chemical properties of the drug (e.g., solubility, molecular size, and stability), intestinal transporters and enzymes are being increasingly implicated in controlling oral drug absorptio

Characterization and topical delivery of phenylethyl resorcinol

Objective: Phenylethyl resorcinol (PR) has been used widely in the personal care industry as a novel skin lightening ingredient. Surprisingly, there is only limited information describing the physicochemical properties of this active. Therefore, the primary objective of this study was to perform a comprehensive characterization of PR. A secondary objective was to investigate the delivery of this molecule to mammalian skin. Methods: Phenylethyl resorcinol was characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and nuclear magnetic resonance (NMR). A new high‐performance liquid chromatographic (HPLC) method for analysis of PR was developed and validated. The log P (octanol water partition coefficient), value, solubility and short‐term stability of PR in a series of vehicles were also determined using HPLC. The evaporation of the selected vehicles was examined using dynamic vapour sorption (DVS). The permeation profiles of PR were investigated under finite dose conditions in porcine and human skin. Results: The melting point of PR was determined to be 79.13 °C and the measured log P (octanol water partition coefficient) at 21 °C was 3.35 ± 0.03. The linearity of the HPLC analytical method was confirmed with an r2 value of 0.99. Accuracy of the method was evaluated by average recovery rates at three tested concentrations, and the values ranged from 99 to 106%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.19 and 0.57 μg mL−1, respectively. The solubility of PR in PG, DMI, glycerol was within the range of 367 to 877 mg mL−1. The stability of PR in tested solvents was also confirmed by the 72 h stability studies. From the DVS studies, 70–125% of applied formulations were recovered at 24 h. The permeation through porcine skin at 24 h ranged from 4 to 13 μg cm−2, while the corresponding amounts of PR delivered through human skin were 2 to 10 μg cm−2. Conclusion: The physicochemical properties of PR confirm it is suitable for dermal delivery. In this study, propylene glycol was the most promising vehicle for PR delivery to human skin. Future work will expand the range of vehicles studied and explore the percutaneous absorption from more complex formulations

Catalyzing a Nursing Response to Healthcare Discrimination Against Transgender and Nonbinary Individuals

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163559/2/jnu12597.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163559/1/jnu12597_am.pd

Characterization of the oral absorption of several aminopenicillins: Determination of intrinsic membrane absorption parameters in the rat intestine in situ

The absorption mechanism of several penicillins was characterized using in situ single-pass intestinal perfusion in the rat. The intrinsic membrane absorption parameters were determined using a modified boundary layer model (fitted value +/- S.E.): J*max = 11.78 +/- 1.88 mM, Km = 15.80 +/- 2.92 mM, P*m = 0, J*c = 0.75 +/- 0.04 for ampicillin; J*max = 0.044 +/- 0.018 mM, Km = 0.058 +/- 0.026 mM, P*m = 0.558 +/- 0.051, P*c = 0.757 +/- 0.088 for amoxicillin; and J*max = 16.30 +/- 3.40 mM, Km = 14.00 +/- 3.30 mM, P*m = 0, P*c = 1.14 +/- 0.05 for cyclacillin. All of the aminopenicillins studied demonstrated saturable absorption kinetics as indicated by their concentration-dependent wall permeabilities. Inhibition studies were performed to confirm the existence of a nonpassive absorption mechanism. The intrinsic wall permeability (P*w) of 0.01 mM ampicillin was significantly lowered by 1 mM amoxicillin and the P*w of 0.01 mM amoxicillin was reduced by 2 mM cephradine consistent with competitive inhibition.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29839/1/0000186.pd