Bacterial reduction of N-oxides of tobacco- specific nitrosamines (TSNA)

1 Contrary to established metabolic pattern, a recent investigation of NNK metabolism produced in rat urine higher levels of 4-(methylnitrosamino)-1-(3-pyridyl)-1- butanone (NNK) and 4-(methylnitrosamino)-1-(3-pyri dyl)-1-butanol (NNAL) than their N-oxides, suggesting that reconversion of N-oxides could occur after urine formation. 2 To verify the possible role of bacteria in the reduction of NNK-N-oxide and NNAL-N-oxide to their respective parent compounds, NNK and NNAL, in smokers with urinary tract infection (UTI), the N-oxides were isolated from the urine of rats treated with 5-3HNNK and individually incubated at 37°C with ten bacterial species in sterile human urine under different pH regimens. After incubation with the bacteria, aliquots of culture media were analyzed by high pressure liquid chromatography (HPLC) with radiochemical detection. 3 Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae and Proteus mirabilis possessed varying capacity to regenerate NNK and NNAL from their N- oxides while others showed no detectable reductive capability within 24 h. 4 This result constitutes the first experimental evidence that in tobacco users with concomitant UTI, bacterial regeneration of the procarcinogenic NNK and NNAL from their N-oxides could occur in the bladder leading to increased carcinogen burden in these individuals

How Much and When Do We Need Higher-order Information in Hypergraphs? A Case Study on Hyperedge Prediction

Hypergraphs provide a natural way of representing group relations, whose complexity motivates an extensive array of prior work to adopt some form of abstraction and simplification of higher-order interactions. However, the following question has yet to be addressed: How much abstraction of group interactions is sufficient in solving a hypergraph task, and how different such results become across datasets? This question, if properly answered, provides a useful engineering guideline on how to trade off between complexity and accuracy of solving a downstream task. To this end, we propose a method of incrementally representing group interactions using a notion of n-projected graph whose accumulation contains information on up to n-way interactions, and quantify the accuracy of solving a task as n grows for various datasets. As a downstream task, we consider hyperedge prediction, an extension of link prediction, which is a canonical task for evaluating graph models. Through experiments on 15 real-world datasets, we draw the following messages: (a) Diminishing returns: small n is enough to achieve accuracy comparable with near-perfect approximations, (b) Troubleshooter: as the task becomes more challenging, larger n brings more benefit, and (c) Irreducibility: datasets whose pairwise interactions do not tell much about higher-order interactions lose much accuracy when reduced to pairwise abstractions

A sense of place, many times over - pattern formation and evolution of repetitive morphological structures

Fifty years ago, Lewis Wolpert introduced the concept of "positional information" to explain how patterns form in a multicellular embryonic field. Using morphogen gradients, whose continuous distributions of positional values are discretized via thresholds into distinct cellular states, he provided, at the theoretical level, an elegant solution to the "French Flag problem." In the intervening years, many experimental studies have lent support to Wolpert's ideas. However, the embryonic patterning of highly repetitive morphological structures, as often occurring in nature, can reveal limitations in the strict implementation of his initial theory, given the number of distinct threshold values that would have to be specified. Here, we review how positional information is complemented to circumvent these inadequacies, to accommodate tissue growth and pattern periodicity. In particular, we focus on functional anatomical assemblies composed of such structures, like the vertebrate spine or tetrapod digits, where the resulting segmented architecture is intrinsically linked to periodic pattern formation and unidirectional growth. These systems integrate positional information and growth with additional patterning cues that, we suggest, increase robustness and evolvability. We discuss different experimental and theoretical models to study such patterning systems, and how the underlying processes are modulated over evolutionary timescales to enable morphological diversification

Drivers of attitudes towards luxury brands: A cross-national investigation into the roles of interpersonal influence and brand consciousness

Purpose - Limited attention has been paid to the cultural influences on the formation of consumer attitudes toward luxury brands (LUX). The current study investigates this relationship by developing a model that additionally employs the constructs of susceptibility to normative interpersonal influence (SNII) and brand consciousness (BCO). Design/methodology/approach - Sample data were gathered through surveys administered to 383 college students in the United Kingdom (UK) and Taiwan. The model of cultural influences on attitudes toward luxury brands was empirically tested using multi-group structural equation modeling to evaluate its applicability across the two countries. Findings - Results are presented in two parts: 1) the exogenous construct part of the model establishing the reliability and validity of the cultural dimension constructs (horizontal individualism, vertical individualism, horizontal collectivism, and vertical collectivism) that are antecedent to consumer SNII and 2) the endogenous part of the model in which consumer SNII affects LUX through the mediating role of BCO. Research limitations/implications - The findings in the current study are limited to a sample of college students in the UK and Taiwan, which, through representing Western and Asian countries, each housing different cultures, do not span the greater number of cultures found across these countries, much less across the world. Furthermore it is assumed that there are a number of subcultures in both the UK and Taiwan that are not accounted for in this study. Practical implications - An individual level of cultural orientation (e.g. horizontalism and verticalism) rather than traditionally adopted regionally-defined or nationally-based (Hofstede, 1980) cultural criteria should be investigated to identify more accurate market demand patterns in order to best target consumers in these markets (Sharma, 2010). In addition, appealing, vertical ad messages would be more effective in stimulating consumer motivations for consumption of luxury brands. Conversely, horizontal ad messages would be effective in demarketing approaches. Originality/value - The current study is the first of its kind to explore the effect of cultural-orientation on the formation of LUX cross-nationally. As such it provides future cross-cultural researchers with valid and reliable culturally-based constructs that can be used to predict consumer SNII in developing LUX. In addition, establishing the mediating role of BCO in the relationship between SNII and LUX helps marketers better understand the equity of their luxury brands, particularly in Asian countries