The development of ‘safer’ compounds for biocidal use

It is important that the biocides industry continues, if not accelerates its moves towards the supply of compounds with lower toxicological thresholds and greater environmental acceptability.Over the last few years a number of pesticides have been classified as harmful to the environment. These have been deleted from company product profiles which has meant that companies have been compelled to develop compounds which are ‘safer’ to use. However, it must be remembered that biocides are designed to kill biological material and the development of the non-toxic biocide is a long way from reality.The obvious but most difficult way to approach this problem, is to develop new active ingredients, however, the cost of such activities is now becoming prohibitive. This does not mean that industry will not continue the search for new biocides, on the contrary in this article such a new group is discussed. What it does mean, is that the development of new active ingredients must run concurrently along with modifications to existing biocidal products and methods of manufacture.     

Split hand and foot deformity and the syndrome of ectrodactyly,ectodermal dysplasia,and clefting (EEC)

Summary Five new cases of ectrodactyly are described. Two patients have the syndrome of ectrodactyly, extodermal dysplasia, and clefting (EEC). In one patient with the EEC syndrome, the disorder seems to represent a new mutation. One woman with isolated ectrodactyly has a daughter with the EEC syndrome. The variation in the clinical expression of this disorder among affected members of the same family makes it difficult to determine whether there may be several mutant alleles responsible for ectrodactyly and its related manifestations.     

The art of strain improvement of industrial lactic acid bacteria without the use of recombinant DNA technology

The food industry is constantly striving to develop new products to fulfil the ever changing demands of consumers and the strict requirements of regulatory agencies. For foods based on microbial fermentation, this pushes the boundaries of microbial performance and requires the constant development of new starter cultures with novel properties. Since the use of ingredients in the food industry is tightly regulated and under close scrutiny by consumers, the use of recombinant DNA technology to improve microbial performance is currently not an option. As a result, the focus for improving strains for microbial fermentation is on classical strain improvement methods. Here we review the use of these techniques to improve the functionality of lactic acid bacteria starter cultures for application in industrial-scale food production. Methods will be described for improving the bacteriophage resistance of specific strains, improving their texture forming ability, increasing their tolerance to stress and modulating both the amount and identity of acids produced during fermentation. In addition, approaches to eliminating undesirable properties will be described. Techniques include random mutagenesis, directed evolution and dominant selection schemes.     

Biocide treatment of biofilms

Biofilms are ubiquitous in nature and microorganisms often exist as members of complex consortia, rather than as pure cultures. Their localised metabolic activity can create diffusion gradients of nutrients, fermentation byproducts and possible associated corrosion products within the biofilms; together with cell lysis, these cause a mosaic of microenvironments which may be totally different to the bathing phase. Such habitats pose a major, and often ignored, constraint on the interpretation of results obtained from laboratory disinfection models which can be physically, environmentally and physiologically inappropriate. For example, the most commonly used model for inactivation of microorganisms by biocides utilises the so-called ‘Chick- Watson law’: this implies that biocide concentration and contact time, the (C × T) factor, are the two key variables determining biocide efficacy. However, applications of the ‘law’ have assumed complete and uniform mixing of microorganisms and biocide, ignoring that diffusion might be rate limiting and that biocide concentration might decrease with time. Recent results suggest that many of the viable bacteria in chlorinated potable water are attached to surfaces and under these circumstances coliforms have withstood at least 12 ppm free residual chlorine. The use and efficacy of alternative biocides such as monochloramine against aquatic biofilms is discussed.     

MicroRNA介导中药活性成分抗肿瘤机制的研究进展

MicroRNA(miRNA)作为一类新发现的非编码RNA,其异常表达在肿瘤的病理过程中扮演着重要角色,起着类似癌基因和抑癌基因的双重作用。目前中药活性成分抗肿瘤已成为关注的热点,但其影响miRNA的报道却较少。就近几年有关中药活性成分、miRNA及肿瘤间关系的研究进行了综述,为今后中药活性成分抗肿瘤的机制研究提供新思路。     

The European economic community and the law of the sea

Abstract

The European Economic Community (EEC) has the competence, to the exclusion of its Member States, to conclude international agreements in important fields, such as fisheries, on which the draft convention on the law of the sea contains provisions. Contracting parties to the future Law of the Sea Convention will not be allowed to make reservations to the convention or participate in it on a partial basis. It follows there‐from that provisions must be envisaged which would allow the EEC to become a contracting party to the convention together with its Member States. This article outlines the legal background for participation by the EEC in international agreements and indicates the main provisions of interest to the EEC in the draft convention prepared at UNCLOS III.     

Plasmids and bacterial resistance to biocides

Plasmid-encoded fu1 bacterial resistance to antibiotics and to anions and cations (including important mercurial and silver compounds) has been widely studied. Plasmid-mediated resistance to organic cationic agents which are important biocides has been described for chlorhexidine and quaternary ammonium compounds (and also for the less important acridines, diamidines and ethidium bromide) in antibiotic-resistant Staphylococcus aureus and Staph. epidermidis strains. Plasmids may also encode reduced biocide susceptibility of Gram-negative bacteria, but intrinsic resistance is likely to be of greater significance. Antibiotic resistance and biocide resistance may be linked but this is not always found clinically.     

Efficacy of biocides used in the modern food industry to control salmonella enterica, and links between biocide tolerance and resistance to clinically relevant antimicrobial compounds

Biocides play an essential role in limiting the spread of infectious disease. The food industry is dependent on these agents, and their increasing use is a matter for concern. Specifically, the emergence of bacteria demonstrating increased tolerance to biocides, coupled with the potential for the development of a phenotype of cross-resistance to clinically important antimicrobial compounds, needs to be assessed. In this study, we investigated the tolerance of a collection of susceptible and multidrug-resistant (MDR) Salmonella enterica strains to a panel of seven commercially available food-grade biocide formulations. We explored their abilities to adapt to these formulations and their active biocidal agents, i.e., triclosan, chlorhexidine, hydrogen peroxide, and benzalkonium chloride, after sequential rounds of in vitro selection. Finally, cross-tolerance of different categories of biocidal formulations, their active agents, and the potential for coselection of resistance to clinically important antibiotics were investigated. Six of seven food-grade biocide formulations were bactericidal at their recommended working concentrations. All showed a reduced activity against both surface-dried and biofilm cultures. A stable phenotype of tolerance to biocide formulations could not be selected. Upon exposure of Salmonella strains to an active biocidal compound, a high-level of tolerance was selected for a number of Salmonella serotypes. No cross-tolerance to the different biocidal agents or food-grade biocide formulations was observed. Most tolerant isolates displayed changes in their patterns of susceptibility to antimicrobial compounds. Food industry biocides are effective against planktonic Salmonella. When exposed to sublethal concentrations of individual active biocidal agents, tolerant isolates may emerge. This emergence was associated with changes in antimicrobial susceptibilities.     

Phenolics with PPAR-gamma ligand-binding activity obtained from licorice (Glycyrrhiza uralensis roots) and ameliorative effects of glycyrin on genetically diabetic KK-A(y) mice

The EtOAc extract of licorice (Glycyrrhiza uralensis roots) exhibited considerable PPAR-gamma ligand-binding activity. Bioassay-guided fractionation of the extract using a GAL-4-PPAR-gamma chimera assay method resulted in the isolation of two isoflavenes, one of which is a new compound named dehydroglyasperin D, an isoflavan, two 3-arylcoumarins, and an isoflavanone as the PPAR-gamma ligand-binding active ingredients of licorice. The isoprenyl group at C-6 and the C-2' hydroxyl group in the aromatic ring-C part in the isoflavan, isoflavene, or arylcoumarin skeleton were found to be the structural requirements for PPAR-gamma ligand-binding activity. Glycyrin, one of the main PPAR-gamma ligands of licorice, significantly decreased the blood glucose levels of genetically diabetic KK-A(y) mice.     

Bacterial target sites for biocide action

Although biocides have been used for a century, the number of products containing biocides has recently increased dramatically with public awareness of hygiene issues. The antimicrobial efficacy of biocides is now well documented; however, there is still a lack of understanding of their antimicrobial mechanisms of action. There is a wide range of biocides showing different levels of antimicrobial activity. It is generally accepted that, in contrast to chemotherapeutic agents, biocides have multiple target sites within the microbial cell and the overall damage to these target sites results in the bactericidal effect. Information about the antimicrobial efficacy of a biocide (i.e. the eta-value) might give some useful indications about the overall mode of action of a biocide. Bacteriostatic effects, usually achieved by a lower concentration of a biocide, might correspond to a reversible activity on the cytoplasmic membrane and/or the impairment of enzymatic activity. The bacteriostatic mechanism(s) of action of a biocide is less documented and a primary (unique?) target site within the cell might be involved. Understanding the mechanism(s) of action of a biocide has become an important issue with the emergence of bacterial resistance to biocides and the suggestion that biocide and antibiotic resistance in bacteria might be linked. There is still a lack of understanding of the mode of action of biocides, especially when used at low concentrations (i.e. minimal inhibitory concentration (MIC) or sublethal). Although this information might not be required for highly reactive biocides (e.g. alkylating and oxidizing agents) and biocides used at high concentrations, the use of biocides as preservatives or in products at sublethal concentrations, in which a bacteriostatic rather than a bactericidal activity is achieved, is driving the need to better understand microbial target sites. Understanding the mechanisms of action of biocides serves several purposes: (i) it will help to design antimicrobial formulations with an improved antimicrobial efficacy and (ii) it will ensure the prevention of the emergence of microbial resistance.     

Disinfection kinetics: a new hypothesis and model for the tailing of log-survivor/time curves

A new hypothesis for the understanding of chemical disinfection, which we have termed the Intrinsic Quenching hypothesis, is presented. This mechanistic treatment of disinfection kinetics is based on the hypothesis that the biocide concentration may not be in vast excess over the microbes, as is normally assumed. A mathematical model was developed and found to be useful in describing the observed kinetics of several disinfectants. The model suggested that the reason for the observation of non-linear, log-survivor curves was due to the ability of the microbes, in clean, soil-free conditions, to intrinsically quench the bulk concentration of biocide.     

Theoretical aspects of enzyme induction and inhibition leading to the reversal of resistance to biocides

The well-known phenomena of enzyme induction and inhibition have been applied in the enunciation of two mechanisms which could be used in the reversal of resistance which organisms develop towards biocides (drugs and pesticides) in many cases. For those biocides active per se which are metabolized by inducible enzymes to non-toxic metabolites, resistant organisms would be those possessing high levels of drug-metabolizing enzymes (Mechanism 1). For those biocides inactive per se but requiring metabolic activation for activity, resistant organisms would be those possessing low levels of drug metabolizing enzymes (Mechanism 2). In mechanism 1, the addition of enzyme inhibitors to the biocide would be effective in reversing resistance. In mechanism 2 the addition of an enzyme inducer to the biocide would increase the susceptibility of the resistant organisms. An ectoparasite insecticide 2-chloro-1-(2,4 dichlorophenyl) vinyl diethylphosphate (chlorfenvinphos or supona) is used as an example for mechanism 1. The malarial drugs primaquine and chloroquine are used as examples of mechanism 2.     

Syndromic ectrodactyly with severe limb, ectodermal, urogenital, and palatal defects maps to chromosome 19.

Congenital limb malformations rank behind only congenital heart disease as the most common birth defects observed in infants. Finding genes that cause defects in human limb patterning should be straightforward but has been limited, in part, by the bewildering spectrum of phenotypes, which are difficult to separate into etiologically distinct disorders. One approach to the identification of relevant genes is to take advantage of unique extended kindreds in which a defect in limb patterning is segregating. Recently, a large Dutch family with ectrodactyly, ectodermal dysplasia, cleft palate, and urogenital defects (EEC) was described by Maas et al. We have studied this kindred and localized a gene causing EEC to a locus on chromosome 19, in a region defined by D19S894 and D19S416. A second extended kindred with EEC does not map to this locus, indicating that EEC is a genetically heterogeneous disorder. Growth and patterning of the limbs, teeth, hair, and genitourinary system are mediated in part by epithelial-mesenchyme inductive interactions. The identification of both the gene causing EEC and its mutation may further elucidate the general signals mediating inductive mechanisms.     

Hygiene,health and environment: European directives

Summary The setting up of the 1993 single market aimed at promoting free movement within the European Community, requires the elaboration of documents intended for the State members, so that the latter may adapt their own national standards which, at the present time, often hinder this free circulation. As for the ?Construction products?, a Directive was passed in this respect on December 21, 1988. It defines six essential requirements applicable to both building and civil engineering works, among which the one entitled: ?Hygiene, Health and Environment?. Each of these requirements will give rise to the elaboration of an ?Interpretative Document? which is aimed at explaining the contents of each requirement, specifying the relevant terminology, allowing the requirements, to be transformed into levels (or classes) of performances to comply with, as well as stating precisely the standards and harmonized technical documents indispensable for both the expression and checking of these levels. With respect to the range of subjects pertinent to the ?Hygiene, Health and Environment? requirement, it should be possible to deal easily with certain aspects such as hydrological cycle, in so far as both regulations and means of verification have, for a long time, been determined in most EEC countries. On the other hand, it will be more difficult to treat other aspects such as: air quality, emission of pollutants or radiation, owing to an almost total absence of any regulations at the present time.     

A green triple biocide cocktail consisting of a biocide, EDDS and methanol for the mitigation of planktonic and sessile sulfate-reducing bacteria

Sulfate-reducing bacteria (SRB) cause souring and their biofilms are often the culprit in Microbiologically Influenced Corrosion (MIC). The two most common green biocides for SRB treatment are tetrakis-hydroxymethylphosphonium sulfate (THPS) and glutaraldehyde. It is unlikely that there will be another equally effective green biocide in the market any time soon. This means more effective biocide treatment probably will rely on biocide cocktails. In this work a triple biocide cocktail consisting of glutaraldehyde or THPS, ethylenediaminedisuccinate (EDDS) and methanol was used to treat planktonic SRB and to remove established SRB biofilms. Desulfovibrio vulgaris (ATCC 7757), a corrosive SRB was used as an example in the tests. Laboratory results indicated that with the addition of 10–15% (v/v) methanol to the glutaraldehyde and EDDS double combination, mitigation of planktonic SRB growth in ATCC 1249 medium and a diluted medium turned from inhibition to a kill effect while the chelator dosage was cut from 2,000 to 1,000 ppm. Biofilm removal was achieved when 50 ppm glutaraldehyde combined with 15% methanol and 1,000 ppm EDDS was used. THPS showed similar effects when it was used to replace glutaraldehyde in the triple biocide cocktail to treat planktonic SRB.     

Efficacy of methylchloro/methylisothiazolone biocide againstLegionella pneumophila in cooling tower water

Summary Methylchloro/methylisothiazolone biocide was tested for efficacy in cooling tower water againstLegionella pneumophila (strains Flint 1 and 2) andL. gormanii. These analyses are the first reports on the efficacy of isothiazolones againstLegionella in actual cooling tower water; the results of data reported previously obtained from more arbitrary laboratory tests are discussed and compared. The biocide was effective in cooling tower water at the two pH levels tested (pH 8.0 and 6.7). The concentration of biocide required to eliminate theL. pneumophila depended on contact time and pH: 99% of the bacteria were killed after 6 and 3 h of contact by 1.07 and 3.13 ppm active ingredient, respectively, when the pH was 8.0: 99% of the bacteria were killed after 6 and 3 h of contact by 2.23 and 9.43 ppm active ingredient, respectively, when the pH was 6.7. 24 h of contact with 0.35 ppm active ingredient methylchloro/methylisothiazolone biocide reduced the concentration of viable bacterial cells by more than four orders of magnitude (>99.99%), regardless of pH.     

Disinfectant testing: use of the Bioscreen Microbiological Growth Analyser for laboratory biocide screening

A new method is described for screening potential biocides based on the traditional suspension test using the Bioscreen optical plate reader. This new method is rapid, reproducible, quantitative and cost effective. Data obtained by this new method are not directly equivalent to the log reduction normally quoted, but give a measurement of the total effect of the biocide on the microbe population, measuring the effect of injury as well as death (non-viability). The method allows for the routine examination of disinfection kinetics, the study of which leads to greater scientific insight into disinfection than that achieved by the standard 5 min, one-point, disinfection tests currently employed.     

四君茶与猴头菇健脾养胃的研究进展

四君茶与猴头菇含有丰富的营养物质与活性成分,是具有较高保健价值的药膳食疗原材料。在越来越提倡“治未病”及“回归自然”的背景下,药膳食疗产品的市场需求和潜力将会得到极大提升。本研究以健脾养胃为靶点,围绕其代表方四君茶与猴头菇的主要成分、药理作用、研究现状、发展前景作一综述,为今后相关药膳产品深入研发提供思路与依据。     

Marine biotechnology advances towards applications in new functional foods

The marine ecosystem is still an untapped reservoir of biologically active compounds, which have considerable potential to supply food ingredients towards development of new functional foods. With the goal of increasing the availability and chemical diversity of functional marine ingredients, much research has been developed using biotechnological tools to discover and produce new compounds.