Broad spectrum antibacterial activity of a mixture of isothiocyanates from nasturtium (Tropaeoli majoris herba) and horseradish (Armoraciae rusticanae radix).

Isothiocyanates have been reported to exert antimicrobial activity. These compounds are found in a licensed native preparation of nasturtium (Tropaeoli majoris herba) and horseradish (Armoraciae rusticanae radix) which is used for treatment of upper respiratory and urinary tract infections. The aim of our investigation was to assess the antimicrobial activity of a mixture of the contained benzyl-, allyl-, and phenylethyl- isothiocyanates against clinically important bacterial and fungal pathogens including antimicrobial resistant isolates. Susceptibility testing was performed by agar-dilution technique. Isothiocyanates were mixed in proportions identical to the licensed drug. Minimum inhibitory- and minimum bactericidal concentrations were assessed. The Minimum inhibitory concentration90 was defined as the concentration which inhibited 90% of the microbial species tested. H. influenzae, M. catarrhalis, S. marcescens, P. vulgaris, and Candida spp. were found to be highly susceptible, with minimum inhibitory concentration90 -values ranging between ≤0.0005% and 0.004% (v/v) of total ITC. Intermediate susceptibilities were observed for S. aureus, S. pyogenes, S. pneumoniae, K. pneumoniae, E. coli and P. aeruginosa, with Minimum inhibitory concentration90 -values ranging between 0.004% and 0.125% (v/v), but with elevated Minimum bactericidal concentrations90-values (2-7 dilution steps above Minimum inhibitory concentration90). Low susceptibilities were determined for viridans streptococci and enterococci. Interestingly, both resistant and non-resistant bacteria were similarly susceptible to the test preparation.

Antimicrobial activity against bacteria with dermatological relevance and skin tolerance of the essential oil from Coriandrum sativum L. fruits.

The aim of this work was to determine the antibacterial activity of essential coriander oil (ECO) on bacteria with dermatological relevance and to assess the skin tolerance of antimicrobial effective ECO concentrations. Essential coriander oil was tested on clinical isolates of different bacteria species, all of which may cause superficial skin infections. Antimicrobial susceptibility testing was performed using a standardized macrodilution test. Essential coriander oil showed good antibacterial activity towards the majority of the bacterial strains tested, including Streptococcus pyogenes (Lancefield group A) and methicillin resistant Staphylococcus aureus (MRSA), with mean minimal inhibitory concentrations of 0.04% v/v and 0.25% v/v, respectively. The skin tolerance of a cream and a lotion containing 0.5% and 1.0% ECO was assessed in 40 healthy volunteers using the occlusive patch test. No skin irritation could be observed by sensitive photometric assessment in any of the volunteers. Because of its activity against Streptococcus pyogenes, Staphylococcus aureus and MRSA combined with excellent skin tolerance, ECO might be useful as an antiseptic for the prevention and treatment of skin infections with Gram-positive bacteria.

First outbreak of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae in Germany.

We report the first outbreak of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae in Germany. The presence of KPC was confirmed by polymerase chain reaction (PCR). The KPC-encoding plasmid was analysed by transconjugation experiments, DNA sequencing, Southern blotting and isoelectric focussing. Typing was performed by pulsed-field gel electrophoresis (PFGE). An ertapenem-resistant K. pneumoniae with low minimum inhibitory concentrations (MIC) to other cabapenems (tested by the Vitek system) was isolated from the index patient in January 2008. A KPC-2 was identified after K. pneumoniae with identical susceptibility patterns had been isolated from two more patients. Despite the introduction of infection control measures, transmission occurred in five additional patients and three of the patients died from infections. The source of the outbreak strain remained unclear; however, the Tn4401-containing bla (KPC-2) gene was similar to previously described isolates from Greece. Five months after the end of the outbreak, a KPC-K. pneumoniae was isolated from a patient who had been treated in Greece previously. Retrospectively, this patient was treated in November 2007 on the same unit as the index case. Typing revealed that all patients were colonised by the same strain. KPC-K. pneumoniae has been introduced to Germany possibly from Greece and transmission to other institutions is likely.

A small chloroplast-encoded protein as a novel architectural component of the light-harvesting antenna.

A small conserved open reading frame in the plastid genome, ycf9, encodes a putative membrane protein of 62 amino acids. To determine the function of this reading frame we have constructed a knockout allele for targeted disruption of ycf9. This allele was introduced into the tobacco plastid genome by biolistic transformation to replace the wild-type ycf9 allele. Homoplasmic ycf9 knockout plants displayed no phenotype under normal growth conditions. However, under low light conditions, their growth rate was significantly reduced as compared with the wild-type, due to a lowered efficiency of the light reaction of photosynthesis. We show that this phenotype is caused by the deficiency in a pigment-protein complex of the light-harvesting antenna of photosystem II and hence by a reduced efficiency of photon capture when light availability is limiting. Our results indicate that, in contrast to the current view, light-harvesting complexes do not only consist of the classical pigment-binding proteins, but may contain small structural subunits in addition. These subunits appear to be crucial architectural factors for the assembly and/or maintenance of stable light-harvesting complexes.

Limitation in electron transfer in photosystem I donor side mutants of Chlamydomonas reinhardtii. Lethal photo-oxidative damage in high light is overcome in a suppressor strain deficient in the assembly of the light harvesting complex.

Strains of Chlamydomonas reinhardtii lacking the PsaF gene or containing the mutation K23Q within the N-terminal part of PsaF are sensitive to high light (>400 microE m(-2) s(-1)) under aerobic conditions. In vitro experiments indicate that the sensitivity to high light of the isolated photosystem I (PSI) complex from wild type and from PsaF mutants is similar. In vivo measurements of photochemical quenching and oxygen evolution show that impairment of the donor side of PSI in the PsaF mutants leads to a diminished linear electron transfer and/or a decrease of photosystem II (PSII) activity in high light. Thermoluminescence measurements indicate that the PSII reaction center is directly affected under photo-oxidative stress when the rate of electron transfer becomes limiting in the PsaF-deficient strain and in the PsaF mutant K23Q. We have isolated a high light-resistant PsaF-deficient suppressor strain that has a high chlorophyll a/b ratio and is affected in the assembly of light-harvesting complex. These results indicate that under high light a functionally intact donor side of PSI is essential for protection of C. reinhardtii against photo-oxidative damage when the photosystems are properly connected to their light-harvesting antennae.

Targeted inactivation of the smallest plastid genome-encoded open reading frame reveals a novel and essential subunit of the cytochrome b(6)f complex.

The smallest conserved open reading frame in the plastid genome, ycf6, potentially specifies a hydrophobic polypeptide of only 29 amino acids. In order to determine the function of this reading frame we have constructed a knockout allele for ycf6. This allele was introduced into the tobacco plastid genome by chloroplast transformation to replace the wild-type ycf6 allele. Homoplasmic Deltaycf6 plants display a photosynthetically incompetent phenotype. Whereas the two photosystems are intact and physiologically active, we found that the electron transfer from photosystem II to photosystem I is interrupted in Deltaycf6 plants. Molecular analyses revealed that this block is caused by the complete absence of the cytochrome b(6)f complex, the redox-coupling complex that interconnects the two photosystems. Analysis of purified cytochrome b(6)f complex by mass spectroscopy revealed the presence of a protein that has exactly the molecular mass calculated for the Ycf6 protein. This suggests that Ycf6 is a genuine subunit of the cytochrome b(6)f complex, which plays a crucial role in complex assembly and/or stability. We therefore propose to rename the ycf6 reading frame petN.

Regulation of nitrate reductase transcript levels by glutamine accumulating in the leaves of a ferredoxin-dependent glutamate synthase-deficient gluS mutant of Arabidopsis thaliana, and by glutamine provided via the roots.

The regulation by glutamine of the leaf transcript level corresponding to the Arabidopsis thaliana (L.) Heynh. nitrate reductase gene nia2 was examined using a novel approach: we took advantage of the ability of a ferredoxin-dependent glutamate synthase-deficient gluS mutant of A. thaliana to accumulate glutamine in the leaves when illuminated under conditions that favour photorespiration. The accumulation of glutamine in gluS mutant leaves and the concomitant decline in the leaf glutamate pool were not correlated with a reduction in the foliar nia2 transcript level. This result indicates that glutamine may not exert a negative control of the leaf nia2 transcript pool. The pattern of diurnal nia2 mRNA oscillation did not change upon illumination of the gluS mutant in air, although the leaf glutamine level remained high during the diurnal cycle. The amplitude of the diurnal fluctuation in nia2 transcript abundance, therefore, does not seem to depend on the size of the leaf glutamine pool (which normally fluctuates in opposite phase). This result also appears to argue against a role of glutamine as an effective repressor of nia2 transcript accumulation. The application of a solution containing 100 mM glutamine to the roots of A. thaliana resulted in an increase in the leaf glutamine level and in a decrease in the leaf nia2 transcript level. Net CO2 uptake and chlorophyll fluorescence quenching by attached leaves of A. thaliana were determined as a control of the physiological status of the plants and remained unaffected by the glutamine treatment. However, there was a decrease in the foliar nitrate level. The negative effect on the nia2 transcript pool exerted by exogeneous glutamine may, therefore, be explained as a result of the down-regulation of nitrate-uptake permeases in the roots by glutamine.

Photosynthesis and fluorescence quenching, and the mRNA levels of plastidic glutamine synthetase or of mitochondrial serine hydroxymethyltransferase (SHMT) in the leaves of the wild-type and of the SHMT-deficient stm mutant of Arabidopsis thaliana in relation to the rate of photorespiration.

The regulation by photorespiration of the transcript level corresponding to plastidic glutamine synthetase (GS-2) was investigated in the leaves of Arabidopsis thaliana (L.) Heynh.. Photorespiration was suppressed by growing the plants in an atmosphere containing 300 Pa CO2. Suppression of photorespiration was demonstrated by the ability of the conditionally lethal serine hydroxymethyltransferase (SHMT)-deficient stm mutant of A. thaliana to grown normally under these conditions. In contrast to previous studies with bean or pea that were performed at very high CO2 partial pressure (2-4 kPa; Edwards and Coruzzi, 1989, Plant Cell 1:241-248; Cock et al., 1991, Plant Mol Biol 17: 761-771), suppression of photorespiration during growth of A. thaliana in an atmosphere with 300 Pa CO2 had no effect of the leaf GS-2 transcript level. In the short term, neither suppression of photorespiration induced by the transfer of air-grown A. thaliana plants into a CO2-enriched atmosphere, nor an increase in the rate of photorespiration achieved by the transfer of high-CO2-grown A. thaliana plants into air resulted in a change in the GS-2 mRNA level. The absence of photorespiratory ammonium release in leaves of the stm mutant had no effect on the GS-2 transcript level. Overall, our data argue against a control by photorespiration of the A. thaliana leaf GS-2 mRNA pool. In contrast, regulation of the leaf SHMT mRNA level may involve a negative feedback effect of at least one metabolite derived from the glycine/serine conversion during photorespiration, as indicated by the overexpression of SHMT transcripts in the leaves of the stm mutant.

Evidence for the Contribution of the Mehler-Peroxidase Reaction in Dissipating Excess Electrons in Drought-Stressed Wheat.

Gross O2 evolution and uptake by attached, drought-stressed leaves of wheat (Triticum aestivum) were measured using a 16O2/ 18O2 isotope technique and mass spectrometry. The activity of photosystem II, determined from the rate of 16O2 evolution, is only slightly affected under drought conditions. During drought stress, net CO2 uptake decreases due to stomatal closure, whereas the uptake of 18O2 is stimulated. The main O2-consuming reactions in the light are the Mehler-peroxidase (MP) reaction and the photorespiratory pathway. From measurements of the rate of carbon flux through the photorespiratory pathway, estimated by the analysis of the specific radioactivities of glycolate, we conclude that the rate of photorespiration is decreased with drought stress. Therefore, the O2 taken up in the light appears to be preferentially used by the MP reaction. In stressed leaves, 29.1% of the photosynthetic electrons are consumed in the MP reaction and 18.4% drive the photorespiratory pathway. Thus, overreduction of the electron transport chain is avoided preferably by the MP reaction when drought stress restricts CO2 reduction.

Comparison of rapid immunofluorescence assay to cell culture isolation for the detection of influenza A and B viruses in nasopharyngeal secretions from infants and children.

In the hospital setting it is often critical to isolate patients appropriately in order to prevent nosocomial infection. This is especially true with respiratory infection in infants and young children. At the present time a rapid immunofluorescence assay (IFA) for respiratory syncytial and parainfluenza viruses is routinely carried out in our laboratory. During January and February of 1990 we used monoclonal antibodies specific for influenza A and B viruses (Baxter-Bartels, Bellevue, WA) in this rapid IFA. 152 samples of NPS were tested by cell culture isolation (CCI) and IFA for the presence of influenza antigens. Twenty-seven samples were positive by both methods, and 114 were negative by both. Three samples were positive by IFA and negative by CCI, while eight samples were positive by CCI and negative by IFA. Five of these eight samples were not positive until 10 to 14 days after inoculation into cell culture, suggesting that the virus inoculum was small. Using CCI as the 'gold' standard, IFA was 90% sensitive and 93% specific. Because of its turn-around time (2-4 h) and acceptable sensitivity and specificity, IFA for influenza viruses will be a routine test in our diagnostic laboratory during the influenza season.

Simultaneous gas exchange and fluorescence measurements indicate differences in the response of sunflower, bean and maize to water stress.

Gas exchange and fluorescence measurements of attached leaves of water stressed bean, sunflower and maize plants were carried out at two light intensities (250 µmol quanta m(-2)s(-1) and 850 µmol quanta m(-2)s(-1)). Besides the restriction of transpiration and CO2 uptake, the dissipation of excess light energy was clearly reflected in the light and dark reactions of photosynthesis under stress conditions. Bean and maize plants preferentially use non-photochemical quenching for light energy dissipation. In sunflower plants, excess light energy gave rise to photochemical quenching. Autoradiography of leaves after photosynthesis in (14)CO2 demonstrated the occurrence of leaf patchiness in sunflower and maize but not in bean. The contribution of CO2 recycling within the leaves to energy dissipation was investigated by studies in 2.5% oxygen to suppress photorespiration. The participation of different energy dissipating mechanisms to quanta comsumption on agriculturally relevant species is discussed.

Ion transport and electrophysiology of the early proximal colon of rabbit.

The ion transport properties of the mammalian descending colon have been the subject of numerous investigations during the last decade. In contrast, relatively few studies have investigated proximal segments of this organ. In the present study, we assessed transepithelial transport of Na+, K+ and Cl- in the isolated initial segment (P1) of rabbit colon in vitro using radioisotopic tracer fluxes and electrophysiological techniques. Like the rabbit descending colon, the proximal colon actively absorbs sodium and chloride, however, its transport systems are markedly different. In vivo, this segment absorbs potassium, however in vitro active potassium secretion was observed. Unlike the descending colon, Na+ absorption is relatively insensitive to amiloride and only a slight inhibition was obtained even at 1 mM concentrations of this drug. Na+ and Cl- absorption appeared to be coupled (directly or indirectly) since the absorption of each ion was inhibited by the removal of the other. Serosal ouabain also inhibited Na+ and Cl- absorption and net K+ secretion. Unlike the descending colon, the proximal P1 segment did not have a net absorptive K+ transport system that was detectable in the presence of ouabain. Electrically, the early proximal colon has a low transepithelial resistance compared to descending colon (RT = 133 +/- 7 omega cm2) but a larger short-circuit current (Isc = 178 +/- 12 microA/cm2). The transepithelial potential averaged -21 +/- 1 mV, in excellent agreement with values measured in vivo. The apical and basolateral membrane potentials averaged -21 +/- 1 mV and -42 +/- 1 mV and intracellular potassium activity was 70 +/- 2 mM.(ABSTRACT TRUNCATED AT 250 WORDS)