Biofilm formation - what we can learn from recent developments.

Although biofilms have been observed early in the history of microbial research, their impact has only recently been fully recognized. Biofilm infections, which contribute to up to 80% of human microbial infections, are associated with common human disorders, such as diabetes mellitus and poor dental hygiene, but also with medical implants. The associated chronic infections such as wound infections, dental caries and periodontitis significantly enhance morbidity, affect quality of life and can aid development of follow-up diseases such as cancer. Biofilm infections remain challenging to treat and antibiotic monotherapy is often insufficient, although some rediscovered traditional compounds have shown surprising efficiency. Innovative anti-biofilm strategies include application of anti-biofilm small molecules, intrinsic or external stimulation of production of reactive molecules, utilization of materials with antimicrobial properties and dispersion of biofilms by digestion of the extracellular matrix, also in combination with physical biofilm breakdown. Although basic principles of biofilm formation have been deciphered, the molecular understanding of the formation and structural organization of various types of biofilms has just begun to emerge. Basic studies of biofilm physiology have also resulted in an unexpected discovery of cyclic dinucleotide second messengers that are involved in interkingdom crosstalk via specific mammalian receptors. These findings even open up new venues for exploring novel anti-biofilm strategies.

Changes in alcohol consumption between 2009 and 2014 assessed with the AUDIT.

BACKGROUND: Alcohol habits in Sweden, assessed as sales and estimates of unrecorded consumption, have changed since joining the EU. Earlier studies using the Alcohol Use Disorders Identification Test (AUDIT) showed that reported consumption is consistent with sales data, which makes it possible to assess consumption according to sex and age. AIMS: This study reports the changes in alcohol habits between 2009 and 2014, a period starting a couple of years after Sweden joined the EU. METHOD: The AUDIT was sent to a random sample of the Swedish population aged between 17 and 80 years old. RESULTS: No statistically significant changes were shown in six age and sex groups. CONCLUSIONS: Alcohol habits have stabilised in Sweden but on a higher consumption level than before.

NOD-like receptor activation by outer membrane vesicles from Vibrio cholerae non-O1 non-O139 strains is modulated by the quorum-sensing regulator HapR.

Vibrio cholerae is an inhabitant of aquatic systems and one of the causative agents of severe dehydrating diarrhea in humans. It has also emerged as an important cause of different kinds of inflammatory responses, and in particular, V. cholerae strains of the non-O1 non-O139 serogroups (NOVC) have been associated with such infections in human. We analyzed the potential of outer membrane vesicles (OMVs) derived from the NOVC strain V:5/04 to induce inflammatory responses in human host cells. V:5/04 OMVs were taken up by human epithelial cells and induced inflammatory responses. Small interfering RNA (siRNA)-mediated gene knockdown revealed that the inflammatory potential of NOVC OMVs was partially mediated by the nucleotide-binding domain-, leucine-rich repeat-containing family member NOD1. Physiochemical analysis of the content of these OMVs, in conjunction with NOD1 and NOD2 reporter assays in HEK293T cells, confirmed the presence of both NOD1 and NOD2 active peptidoglycan in the OMVs. Furthermore, we show that deletion of the quorum-sensing regulator HapR, which mimics an infective life style, specifically reduced the inflammatory potential of the V:5/04 OMVs and their ability to activate NOD1 and NOD2. In conclusion, our study shows that NOVC OMVs elicit immune responses mediated by NOD1 and NOD2 in mammalian host cells. Moreover, we provide evidence that the quorum-sensing machinery plays an important regulatory role in this process by attenuating the inflammatory potential of OMVs under infective conditions. This work thus identifies a new facet of how Vibrio affects host immune responses and defines a role for the quorum-sensing machinery in this process.

Per capita alcohol consumption and liver cirrhosis mortality in 14 European countries.

AIM: To estimate the effects of changes in per capita alcohol consumption on liver cirrhosis mortality rates in various demographic groups across 14 western European countries. METHOD: Yearly changes in gender- and age-specific mortality rates from 1950 to 1995 were analysed in relation to corresponding yearly changes in per capita alcohol consumption, employing the Box-Jenkins technique for time series analysis. Country-specific estimates were pooled into three regions: northern, central and southern Europe. MEASUREMENTS: Cirrhosis mortality data for 5-year age groups were converted into gender-specific mortality rates in the age groups 15+, 15-44, 45-64 and 65+ and expressed as the number of deaths per 100,000 inhabitants. Alcohol sales were used to measure aggregate consumption, which were calculated into consumption (litres 100% alcohol) per year per inhabitant over 14 years of age and weighted with a 10-year distributed lag model. FINDINGS: The country-specific analyses demonstrated a positive and statistically significant effect of changes in per capita consumption on changes in cirrhosis mortality in 13 countries for males and in nine countries for females. The strongest alcohol effect was found in northern Europe, due mainly to a large effect in Sweden. Moreover, when different age groups were analysed significant estimates were obtained in 29 of 42 cases for males and in 20 of 42 cases for females. Most of the non-significant estimates were found in older age groups. CONCLUSIONS: The results suggest clearly that a change in the overall level of drinking as a general rule affect cirrhosis mortality in different drinking cultures as well as among different demographic groups. Moreover, the findings correspond with what is expected from the collectivity theory of drinking cultures.

Alcohol and suicide in 14 European countries.

AIMS: To test the hypothesis that a positive population-level relationship between alcohol and suicide is more likely to be found in dry drinking cultures (as indicated by consumption level) than in wet drinking cultures. DESIGN: Gender- and age-specific suicide rates in 14 western European countries were analysed in relation to per capita alcohol consumption employing the Box-Jenkins technique for time series analysis. The country-specific estimates were pooled into low-, medium- and high-consumption countries. MEASUREMENTS: Suicide mortality data for 5-year age groups were converted into gender- and age-specific mortality rates. Alcohol sales expressed as litres of 100% alcohol per year and inhabitants 15 years and older were used as a measure of alcohol consumption. FINDINGS: A positive and significant relationship between per capita consumption and gender- and age-specific suicide rates was revealed most often in northern Europe and found least often in southern Europe. A stronger absolute alcohol effect for men was found only in northern Europe, whereas the relative alcohol effect was somewhat stronger for women in both northern and central Europe. Also, the suicide rate in younger age groups was more often significantly related to per capita consumption than suicide among the elder in northern and central Europe but not in southern Europe. CONCLUSIONS: The population-level association between alcohol and suicide is conditioned by cultural factors. In general, the suicide rate tends to be more responsive to changes in alcohol consumption in drinking cultures characterized by a low post-war per capita consumption compared to drinking cultures with higher consumption levels. The findings give support to the hypothesis derived from previous theoretical and empirical work, suggesting that suicide and alcohol is more closely connected in dry cultures than in wet cultures.

Components of resistance of leaf rust (Melamspora laricii epitea Kleb./Melampsora ribesii-viminalis Kleb.) in Salix viminalis L.

Selection on partial resistance components, namely latent period, development rate of uredia and number and size of uredia, has been suggested as a means to achieve durable resistance. Three experiments were carried out in growth chambers to assess the impact of environmental and genetic factors on these components in the Salix-Melampsora host-pathogen system. They confirmed the environmental ability of the Melampsora-Salicaceae relationship and provided no definite answer on the possibility of attaining durable resistance through selection on partial resistance components. On the one hand, there is a large amount of heritable variation among clones for most components; on the other hand, all components were extremely sensitive to environmental conditions and isolates, making the development of standard selection methods difficult.

Carbohydrate and Amino Acid Metabolism in the Ectomycorrhizal Ascomycete Sphaerosporella brunnea during Glucose Utilization : A C NMR Study.

Nuclear magnetic resonance spectroscopy was utilized to study the metabolism of [1-(13)C]glucose in mycelia of the ectomycorrhizal ascomycete Sphaerosporella brunnea. The main purpose was to assess the biochemical pathways for the assimilation of glucose and to identify the compounds accumulated during glucose assimilation. The majority of the (13)C label was incorporated into mannitol, while glycogen, trehalose and free amino acids were labeled to a much lesser extent. The high enrichment of the C1/C6 position of mannitol indicated that the polyol was formed via a direct route from absorbed glucose. Randomization of the (13)C label was observed to occur in glucose and trehalose leading to the accumulation of [1,6-(13)C]trehalose and [1,6-(13)C]glucose. This suggests that the majority of the glucose carbon used to form trehalose was cycled through the metabolically active mannitol pool. The proportion of label entering the free amino acids represented 38% of the soluble (13)C after 6 hours of continuous glucose labeling. Therefore, amino acid biosynthesis is an important sink of assimilated carbon. Carbon-13 was incorporated into [3-(13)C]alanine and [2-(13)C]-, [3-(13)C]-, and [4-(13)C]glutamate and glutamine. From the analysis of the intramolecular (13)C enrichment of these amino acids, it is concluded that [3-(13)C]pyruvate, arising from [1-(13)C]glucose catabolism, was used by alanine aminotransferase, pyruvate dehydrogenase, and pyruvate carboxylase (or phosphoenolpyruvate carboxykinase). Intramolecular (13)C labeling patterns of glutamate and glutamine were similar and are consistent with the operation of the Krebs cycle. There is strong evidence for (a) randomization of the label on C2 and C3 positions of oxaloacetate via malate dehydrogenase and fumarase, and (b) the dual biosynthetic and respiratory role of the citrate synthase, aconitase, and isocitrate dehydrogenase reactions. The high flux of carbon through the carboxylation (presumably pyruvate carboxylase) step indicates that CO(2) fixation is an important component of the carbon metabolism in S. brunnea, and it is likely that this anaplerotic role is particularly prevalent during NH(4) (+) assimilation. The most relevant information resulting from this investigation is (a) the occurrence of the mannitol cycle, (b) a large part of the trehalose pool is synthesized after the cycling of glucose-carbon through the mannitol cycle, and (c) pyruvate (or phosphoenolpyruvate) carboxylation plays an important role in the primary metabolism of glucose-fed mycelia.

Carbon and nitrogen metabolism in ectomycorrhizal fungi and ectomycorrhizas.

The literature concerning the metabolism of carbon and nitrogen compounds in ectomycorrhizal associations of trees is reviewed. The absorption and translocation of mineral ions by the mycelia require an energy source and a reductant which are both supplied by respiratory catabolism of carbohydrates produced by the host plant. Photosynthates are also required to generate the carbon skeletons for amino acid and carbohydrate syntheses during the growth of the mycelia. Competition for photosynthates occurs between the fungal cells and the various vegetative sinks in the host tree. The nature of carbon compounds involved in these processes, their routes of metabolism, the mechanisms of control and the partitioning of metabolites between the various sites of utilization are only poorly understood. Both ascomycetous and basidiomycetous ectomycorrhizal fungi synthesize and some, if not all, accumulate mannitol, trehalose and triglycerides. The fungal strains employ the Embden--Meyerhof pathway of glucose catabolism and the key enzymes of the pentose phosphate pathway (6-phosphogluconate dehydrogenase, glucose-6-phosphate dehydrogenase, transaldolase and transketolase). Anaplerotic CO2 fixation, via pyruvate carboxylase and/or phosphoenolpyruvate carboxykinase, provides high pools of amino acids. This process could be important in the recapture and assimilation of respired CO2 in the rhizosphere. The ectomycorrhizas are thought to contain the Embden--Meyerhof pathway, the pentose phosphate pathway and the tricarboxylic acid cycle, which provide the carbon skeletons for the assimilation of ammonia into amino acids. The main route of assimilation of ammonia appears to be through the glutamine synthetase-glutamate synthase cycle in the ectomycorrhizas. Glutamate dehydrogenase plays a minor role in this process. Glutamate dehydrogenase and glutamine synthetase are present in free-living ectomycorrhizal fungi and they participate in the assimilation of ammonia and the synthesis of amino acids through the glutamate dehydrogenase/glutamine synthetase sequence. In both in vitro cultures of fungi and ectomycorrhizas, the assimilated nitrogen accumulates in glutamine. Glutamine, but also ammonia, are thought to be exported from the fungal tissues to the host cells. Studies on the metabolism of ectomycorrhizas and ectomycorrhizal fungi have focused on the metabolic pathways and compounds which accumulate in the symbiotic tissues. Studies on regulation of the overall process, and the control of enzyme activity in particular, are still fragmentary.(ABSTRACT TRUNCATED AT 400 WORDS)

Hemocyte lysate enhancement of fungal spore encapsulation by crayfish hemocytes.

Crayfish hemocytes exhibited a stronger encapsulation reaction to fungal blastospores of Beauveria bassiana coated with hemocyte lysate, than to blastospores treated with plasma or buffer, indicating an opsonic function of hemocyte lysate proteins. Five proteins of the prophenoloxidase activating system in the hemocytes were attached to foreign surfaces (including the blastospores) after activation and it is suggested that these attaching proteins (one being phenoloxidase) are responsible for the opsonic function of the hemocyte lysate on crayfish blood cells.